secondary airflow is not detectable in the exhaust system during the
check. For engines equipped with positive crankcase ventilation (PCV),
monitoring of the PCV system is not necessary provided the manufacturer
can demonstrate to the Administrator's satisfaction that the PCV system
is unlikely to fail.
    (ii) Diesel. Any deterioration or malfunction occurring in an
engine system or component directly intended to control emissions,
including but not necessarily limited to, the exhaust gas

recirculation (EGR) system, if equipped, and the fuel control system,
singularly resulting in exhaust emissions exceeding any of the
following levels: The applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr
PM, whichever is higher; or, 1.75 times the applicable NOX
standard for engines certified to a NOX FEL greater than
0.50 g/bhp-hr; or, the applicable NOX FEL+0.5 g/bhp-hr for
engines certified to a NOX FEL less than or equal to 0.50 g/
bhp-hr; or, 2.5 times the applicable NMHC standard; or, 2.5 times the
applicable CO standard. A functional check, as described in Sec.
86.005-17(b)(6), may satisfy the requirements of this paragraph (b)(5)
provided the manufacturer can demonstrate that a malfunction would not
cause emissions to exceed the applicable levels. This demonstration is
subject to Administrator approval. For engines equipped with crankcase
ventilation (CV), monitoring of the CV system is not necessary provided
the manufacturer can demonstrate to the Administrator's satisfaction
that the CV system is unlikely to fail.
    (b)(6) [Reserved]. For guidance see Sec.  86.005-17.
    (b)(7) Performance of OBD functions. Any sensor or other component
deterioration or malfunction which renders that sensor or component
incapable of performing its function as part of the OBD system must be
detected and identified on engines so equipped.
    (c), (d), (e), (f), (g), and (h)(1)(i) through (h)(1)(iv)
[Reserved]. For guidance see Sec.  86.005-17.
    (h)(1)(v) All acronyms, definitions and abbreviations shall be
formatted according to SAE J1930 ``Electrical/Electronic Systems
Diagnostic Terms, Definitions, Abbreviations, and Acronyms Equivalent
to ISO/TR 15031-2: April 30, 2002'', (Revised, April 2002), or SAE
J2403, ``Medium/Heavy-Duty E/E Systems Diagnosis Nomenclature: August
2004.''
    (h)(1)(vi) through (h)(3) [Reserved]. For guidance see Sec.
86.005-17.
    (i) Deficiencies and alternative fueled engines. Upon application
by the manufacturer, the Administrator may accept an OBD system as
compliant even though specific requirements are not fully met. Such
compliances without meeting specific requirements, or deficiencies,
will be granted only if compliance would be infeasible or unreasonable
considering such factors as, but not limited to: Technical feasibility
of the given monitor and lead time and production cycles including
phase-in or phase-out of engines or vehicle designs and programmed
upgrades of computers. Unmet requirements should not be carried over
from the previous model year except where unreasonable hardware or
software modifications would be necessary to correct the deficiency,
and the manufacturer has demonstrated an acceptable level of effort
toward compliance as determined by the Administrator. Furthermore, EPA
will not accept any deficiency requests that include the complete lack
of a major diagnostic monitor (``major'' diagnostic monitors being
those for exhaust aftertreatment devices, oxygen sensor, air-fuel ratio
sensor, NOX sensor, engine misfire, evaporative leaks, and
diesel EGR, if equipped), with the possible exception of the special
provisions for alternative fueled engines. For alternative fueled
heavy-duty engines (e.g. natural gas, liquefied petroleum gas,
methanol, ethanol), manufacturers may request the Administrator to
waive specific monitoring requirements of this section for which
monitoring may not be reliable with respect to the use of the
alternative fuel. At a minimum, alternative fuel engines must be
equipped with an OBD system meeting OBD requirements to the extent
feasible as approved by the Administrator.
    (j) California OBDII compliance option. For heavy-duty engines used
in applications weighing 14,000 pounds GVWR or less, demonstration of
compliance with California OBD II requirements (Title 13 California
Code of Regulations section 1968.2 (13 CCR 1968.2)), as modified and
released on August 11, 2006, shall satisfy the requirements of this
section, except that compliance with 13 CCR 1968.2(e)(4.2.2)(C),
pertaining to 0.02 inch evaporative leak detection, and 13 CCR
1968.2(d)(1.4), pertaining to tampering protection, are not required to
satisfy the requirements of this section. Also, the deficiency
provisions of 13 CCR 1968.2(k) do not apply. The deficiency provisions
of paragraph (i) of this section and the evaporative leak detection
requirement of Sec.  86.005-17(b)(4) apply to manufacturers selecting
this paragraph for demonstrating compliance. In addition, demonstration
of compliance with 13 CCR 1968.2(e)(15.2.1)(C), to the extent it
applies to the verification of proper alignment between the camshaft
and crankshaft, applies only to vehicles equipped with variable valve
timing.
    (k) [Reserved]. For guidance see Sec.  86.005-17.
    4. Section 86.007-30 is added to Subpart A to read as follows:
    Section 86.007-30 includes text that specifies requirements that
differ from Sec. Sec.  86.094-30, 86.095-30, 86.096-30, 86.098-30,
86.001-30 or 86.004-30. Where a paragraph in Sec.  86.094-30, Sec.
86.095-30, Sec.  86.096-30, Sec.  86.098-30, Sec.  86.001-30 or Sec.
86.004-30 is identical and applicable to Sec.  86.007-30, this may be
indicated by specifying the corresponding paragraph and the statement
``[Reserved]. For guidance see Sec.  86.094-30.'' or ``[Reserved]. For
guidance see Sec.  86.095-30.'' or ``[Reserved]. For guidance see Sec.
86.096-30.'' or ``[Reserved]. For guidance see Sec.  86.098-30.'' or
``[Reserved]. For guidance see Sec.  86.001-30.'' or ``[Reserved]. For
guidance see 86.004-30.''

Sec.  86.007-30  Certification.

    (a)(1) and (a)(2) [Reserved]. For guidance see Sec.  86.094-30.
    (a)(3)(i) through (a)(4)(ii) [Reserved]. For guidance see Sec.
86.004-30.
    (a)(4)(iii) introductory text through (a)(4)(iii)(C) [Reserved].
For guidance see Sec.  86.094-30.
    (a)(4)(iv) introductory text [Reserved]. For guidance see Sec.
86.095-30.
    (a)(4)(iv)(A)-(a)(9) [Reserved]. For guidance see Sec.  86.094-30.
    (a)(10) and (a)(11) [Reserved]. For guidance see Sec.  86.004-30.
    (a)(12) [Reserved]. For guidance see Sec.  86.094-30.
    (a)(13) [Reserved]. For guidance see Sec.  86.095-30.
    (a)(14) [Reserved]. For guidance see Sec.  86.094-30.
    (a) (15)-(18) [Reserved]. For guidance see Sec.  86.096-30.
    (a)(19) [Reserved]. For guidance see Sec.  86.098-30.
    (a)(20) [Reserved]. For guidance see Sec.  86.001-30.
    (a)(21) [Reserved]. For guidance see Sec.  86.004-30.
    (b)(1) introductory text through (b)(1)(ii)(A) [Reserved]. For
guidance see Sec.  86.094-30.
    (b)(1)(ii)(B) [Reserved]. For guidance see Sec.  86.004-30.
    (b)(1)(ii)(C) [Reserved]. For guidance see Sec.  86.094-30.
    (b)(1)(ii)(D) [Reserved]. For guidance see Sec.  86.004-30.
    (b)(1)(iii) and (b)(1)(iv) [Reserved]. For guidance see Sec.
86.094-30.
    (b)(2) [Reserved]. For guidance see Sec.  86.098-30.
    (b)(3)-(b)(4)(i) [Reserved]. For guidance see Sec.  86.094-30.
    (b)(4)(ii) introductory text [Reserved]. For guidance see Sec.
86.098-30.
    (b)(4)(ii)(A) [Reserved]. For guidance see Sec.  86.094-30.
    (b)(4)(ii)(B)-(b)(4)(iv) [Reserved]. For guidance see Sec.  86.098-
30.
    (b)(5)-(e) [Reserved]. For guidance see Sec.  86.094-30.
    (f) introductory text through (f)(1)(i) [Reserved]. For guidance
see Sec.  86.004-30.

    (f)(1)(ii) Diesel.
    (A) If monitored for emissions performance--a catalyst is replaced
with a deteriorated or defective catalyst, or an electronic simulation
of such, resulting in exhaust emissions exceeding 1.75 times the
applicable NOX standard for engines certified to a
NOX FEL greater than 0.50 g/bhp-hr; or, the applicable
NOX FEL+0.5 g/bhp-hr for engines certified to a
NOX FEL less than or equal to 0.50 g/bhp-hr. This
requirement applies only to reduction catalysts.
    (B) If monitored for performance--a particulate trap is replaced
with a trap that has catastrophically failed, or an electronic
simulation of such.
    (f)(2) [Reserved]. For guidance see Sec.  86.004-30.
    (f)(3)(i) Oxygen sensors and air-fuel ratio sensors downstream of
aftertreatment devices.
    (A) Otto-cycle. If so equipped, any oxygen sensor or air-fuel ratio
sensor located downstream of aftertreatment devices is replaced with a
deteriorated or defective sensor, or an electronic simulation of such,
resulting in exhaust emissions exceeding 1.5 times the applicable
standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If so equipped, any oxygen sensor or air-fuel ratio
sensor located downstream of aftertreatment devices is replaced with a
deteriorated or defective sensor, or an electronic simulation of such,
resulting in exhaust emissions exceeding any of the following levels:
the applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, whichever is
higher; or, 1.75 times the applicable NOX standard for
engines certified to a NOX FEL greater than 0.50 g/bhp-hr;
or, the applicable NOX FEL+0.5 g/bhp-hr for engines
certified to a NOX FEL less than or equal to 0.50 g/bhp-hr;
or, 2.5 times the applicable NMHC standard.
    (ii) Oxygen sensors and air-fuel ratio sensors upstream of
aftertreatment devices.
    (A) Otto-cycle. If so equipped, any oxygen sensor or air-fuel ratio
sensor located upstream of aftertreatment devices is replaced with a
deteriorated or defective sensor, or an electronic simulation of such,
resulting in exhaust emissions exceeding 1.5 times the applicable
standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If so equipped, any oxygen sensor or air-fuel ratio
sensor located upstream of aftertreatment devices is replaced with a
deteriorated or defective sensor, or an electronic simulation of such,
resulting in exhaust emissions exceeding any of the following levels:
the applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, whichever is
higher; or, 1.75 times the applicable NOX standard for
engines certified to a NOX FEL greater than 0.50 g/bhp-hr;
or, the applicable NOX FEL+0.5 g/bhp-hr for engines
certified to a NOX FEL less than or equal to 0.50 g/bhp-hr;
or, 2.5 times the applicable NMHC standard; or, 2.5 times the
applicable CO standard.
    (iii) NOX sensors.
    (A) Otto-cycle. If so equipped, any NOX sensor is
replaced with a deteriorated or defective sensor, or an electronic
simulation of such, resulting in exhaust emissions exceeding 1.5 times
the applicable standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If so equipped, any NOX sensor is replaced
with a deteriorated or defective sensor, or an electronic simulation of
such, resulting in exhaust emissions exceeding any of the following
levels: the applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM,
whichever is higher; or, 1.75 times the applicable NOX
standard for engines certified to a NOX FEL greater than
0.50 g/bhp-hr; or, the applicable NOX FEL+0.5 g/bhp-hr for
engines certified to a NOX FEL less than or equal to 0.50 g/
bhp-hr.
    (f)(4) [Reserved]. For guidance see Sec.  86.004-30.
    (f)(5)(i) Otto-cycle. A malfunction condition is induced in any
emission-related engine system or component, including but not
necessarily limited to, the exhaust gas recirculation (EGR) system, if
equipped, the secondary air system, if equipped, and the fuel control
system, singularly resulting in exhaust emissions exceeding 1.5 times
the applicable emission standard or FEL for NMHC, NOX, or
CO.
    (ii) Diesel. A malfunction condition is induced in any emission-
related engine system or component, including but not necessarily
limited to, the exhaust gas recirculation (EGR) system, if equipped,
and the fuel control system, singularly resulting in exhaust emissions
exceeding any of the following levels: the applicable PM FEL+0.04 g/
bhp-hr or 0.05 g/bhp-hr PM, whichever is higher; or, 1.75 times the
applicable NOX standard for engines certified to a
NOX FEL greater than 0.50 g/bhp-hr; or, the applicable
NOX FEL+0.5 g/bhp-hr for engines certified to a
NOX FEL less than or equal to 0.50 g/bhp-hr; or, 2.5 times
the applicable NMHC standard; or, 2.5 times the applicable CO standard.
    (f)(6) [Reserved]. For guidance see Sec.  86.004-30.
    5. Section 86.010-2 is added to Subpart A to read as follows:

Sec.  86.010-2  Definitions.

    The definitions of Sec.  86.004-2 continue to apply to 2004 and
later model year vehicles. The definitions listed in this section apply
beginning with the 2010 model year.
    Drive cycle or driving cycle means operation that consists of
engine startup and engine shutoff during which a given onboard
diagnostic (OBD) monitor makes a diagnostic decision. A drive cycle
need not consist of all OBD monitors making a diagnostic decision
during the engine startup and engine shutoff cycle. An engine restart
following an engine shutoff that has been neither commanded by the
vehicle operator nor by the engine control strategy but caused by an
event such as an engine stall may be considered a new drive cycle or a
continuation of the existing drive cycle.
    DTC means diagnostic trouble code.
    Engine start as used in Sec.  86.010-18 means the point when the
engine reaches a speed 150 rpm below the normal, warmed-up idle speed
(as determined in the drive position for vehicles equipped with an
automatic transmission). For hybrid vehicles or for engines employing
alternative engine start hardware or strategies (e.g., integrated
starter and generators.), the manufacturer may use an alternative
definition for engine start (e.g., key-on) provided the alternative
definition is based on equivalence to an engine start for a
conventional vehicle.
    Functional check, in the context of onboard diagnostics, means
verifying that a component and/or system that receives information from
a control computer responds properly to a command from the control
computer.
    Ignition cycle as used in Sec.  86.010-18 means a cycle that begins
with engine start, meets the engine start definition for at least two
seconds plus or minus one second, and ends with engine shutoff.
    Limp-home operation as used in Sec.  86.010-18 means an operating
mode that an engine is designed to enter upon determining that normal
operation cannot be maintained. In general, limp-home operation implies
that a component or system is not operating properly or is believed to
be not operating properly.
    Malfunction means the conditions have been met that require the
activation of an OBD malfunction indicator light and storage of a DTC.
    MIL-on DTC means the diagnostic trouble code stored when an OBD
system has detected and confirmed that a malfunction exists (e.g.,
typically on the second drive cycle during which a given OBD monitor
has evaluated a system or component). Industry standards may refer to
this as a confirmed or an active DTC.

    Pending DTC means the diagnostic trouble code stored upon the
detection of a potential malfunction.
    Permanent DTC means a DTC that corresponds to a MIL-on DTC and is
stored in non-volatile random access memory (NVRAM). A permanent DTC
can only be erased by the OBD system itself and cannot be erased
through human interaction with the OBD system or any onboard computer.
    Previous-MIL-on DTC means a DTC that corresponds to a MIL-on DTC
but is distinguished by representing a malfunction that the OBD system
has determined no longer exists but for which insufficient operation
has occurred to satisfy the DTC erasure provisions.
    Potential malfunction means that conditions have been detected that
meet the OBD malfunction criteria but for which more drive cycles are
allowed to provide further evaluation prior to confirming that a
malfunction exists.
    Rationality check, in the context of onboard diagnostics, means
verifying that a component that provides input to a control computer
provides an accurate input to the control computer while in the range
of normal operation and when compared to all other available
information.
    Similar conditions, in the context of onboard diagnostics, means
engine conditions having an engine speed within 375 rpm, load
conditions within 20 percent, and the same warm up status (i.e., cold
or hot). The manufacturer may use other definitions of similar
conditions based on comparable timeliness and reliability in detecting
similar engine operation.
    6. Section 86.010-17 is added to Subpart A to read as follows:

Sec.  86.010-17  On-board Diagnostics for engines used in applications
less than or equal to 14,000 pounds GVWR.

    Section 86.010-17 includes text that specifies requirements that
differ from Sec.  86.005-17 and Sec.  86.007-17. Where a paragraph in
Sec.  86.005-17 or Sec.  86.007-17 is identical and applicable to Sec.
86.010-17, this may be indicated by specifying the corresponding
paragraph and the statement ``[Reserved]. For guidance see Sec.
86.005-17.'' or ``[Reserved]. For guidance see Sec.  86.007-17.''
    (a) General.
    (1) All heavy-duty engines intended for use in a heavy-duty vehicle
weighing 14,000 pounds GVWR or less must be equipped with an on-board
diagnostic (OBD) system capable of monitoring all emission-related
engine systems or components during the applicable useful life. All
monitored systems and components must be evaluated periodically, but no
less frequently than once per applicable certification test cycle as
defined in Appendix I, paragraph (f), of this part, or similar trip as
approved by the Administrator.
    (2) An OBD system demonstrated to fully meet the requirements in
Sec.  86.1806-10 may be used to meet the requirements of this section,
provided that the Administrator finds that a manufacturer's decision to
use the flexibility in this paragraph (a)(2) is based on good
engineering judgment.
    (b) Introductory text and (b)(1)(i) [Reserved]. For guidance see
Sec.  86.005-17.
    (b)(1)(ii) Diesel.
    (A) If equipped, reduction catalyst deterioration or malfunction
before it results in exhaust NOX emissions exceeding the
applicable NOX FEL+0.3 g/bhp-hr. If equipped, oxidation
catalyst deterioration or malfunction before it results in exhaust NMHC
emissions exceeding 2.5 times the applicable NMHC standard. These
catalyst monitoring requirements need not be done if the manufacturer
can demonstrate that deterioration or malfunction of the system will
not result in exceedance of the threshold.
    (B) If equipped, diesel particulate trap deterioration or
malfunction before it results in exhaust emissions exceeding any of the
following levels: The applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr
PM, whichever is higher; or, exhaust NMHC emissions exceeding 2.5 times
the applicable NMHC standard. Catastrophic failure of the particulate
trap must also be detected. In addition, the absence of the particulate
trap or the trapping substrate must be detected.
    (b)(2) [Reserved]. For guidance see Sec.  86.005-17.
    (b)(3)(i) Oxygen sensors and air-fuel ratio sensors downstream of
aftertreatment devices.
    (A) Otto-cycle. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding 1.5 times the applicable
standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding any of the following levels:
the applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, whichever is
higher; or, the applicable NOX FEL+0.3 g/bhp-hr; or, 2.5
times the applicable NMHC standard.
    (ii) Oxygen sensors and air-fuel ratio sensors upstream of
aftertreatment devices.
    (A) Otto-cycle. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding 1.5 times the applicable
standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding any of the following levels:
the applicable PM FEL+0.02 g/bhp-hr or 0.03 g/bhp-hr PM, whichever is
higher; or, the applicable NOX FEL+0.3 g/bhp-hr; or, 2.5
times the applicable NMHC standard; or, 2.5 times the applicable CO
standard.
    (iii) NOX sensors.
    (A) Otto-cycle. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding 1.5 times the applicable
standard or FEL for NMHC, NOX or CO.
    (B) Diesel. If equipped, sensor deterioration or malfunction
resulting in exhaust emissions exceeding any of the following levels:
the applicable PM FEL+0.04 g/bhp-hr or 0.05 g/bhp-hr PM, whichever is
higher; or, the applicable NOX FEL+0.3 g/bhp-hr.
    (b)(4) [Reserved]. For guidance see Sec.  86.005-17.
    (b)(5) Other emission control systems and components.
    (i) Otto-cycle. Any deterioration or malfunction occurring in an
engine system or component directly intended to control emissions,
including but not necessarily limited to, the exhaust gas recirculation
(EGR) system, if equipped, the secondary air system, if equipped, and
the fuel control system, singularly resulting in exhaust emissions
exceeding 1.5 times the applicable emission standard or FEL for NMHC,
NOX or CO. For engines equipped with a secondary air system,
a functional check, as described in Sec.  86.005-17(b)(6), may satisfy
the requirements of this paragraph (b)(5) provided the manufacturer can
demonstrate that deterioration of the flow distribution system is
unlikely. This demonstration is subject to Administrator approval and,
if the demonstration and associated functional check are approved, the
diagnostic system must indicate a malfunction when some degree of
secondary airflow is not detectable in the exhaust system during the
check. For engines equipped with positive crankcase ventilation (PCV),
monitoring of the PCV system is not necessary provided the manufacturer
can demonstrate to the Administrator's satisfaction that the PCV system
is unlikely to fail.
    (ii) Diesel. Any deterioration or malfunction occurring in an
engine system or component directly intended to control emissions,
including but not necessarily limited to, the exhaust gas recirculation
(EGR) system, if equipped, and the fuel control system, singularly
resulting in exhaust emissions

exceeding any of the following levels: the applicable PM FEL+0.02 g/
bhp-hr or 0.03 g/bhp-hr PM, whichever is higher; or, the applicable
NOX FEL+0.3 g/bhp-hr; or, 2.5x the applicable NMHC standard;
or, 2.5x the applicable CO standard. A functional check, as described
in Sec.  86.005-17(b)(6), may satisfy the requirements of this
paragraph (b)(5) provided the manufacturer can demonstrate that a
malfunction would not cause emissions to exceed the applicable levels.
This demonstration is subject to Administrator approval. For engines
equipped with crankcase ventilation (CV), monitoring of the CV system
is not necessary provided the manufacturer can demonstrate to the
Administrator's satisfaction that the CV system is unlikely to fail.
    (b)(6) [Reserved]. For guidance see Sec.  86.005-17.
    (b)(7) [Reserved]. For guidance see Sec.  86.007-17.
    (c) [Reserved]. For guidance see Sec.  86.005-17.
    (d) MIL illumination.
    (1) The MIL must illuminate and remain illuminated when any of the
conditions specified in paragraph (b) of this section are detected and
verified, or whenever the engine control enters a default or secondary
mode of operation considered abnormal for the given engine operating
conditions. The MIL must blink once per second under any period of
operation during which engine misfire is occurring and catalyst damage
is imminent. If such misfire is detected again during the following
driving cycle (i.e., operation consisting of, at a minimum, engine
start-up and engine shut-off) or the next driving cycle in which
similar conditions are encountered, the MIL must maintain a steady
illumination when the misfire is not occurring and then remain
illuminated until the MIL extinguishing criteria of this section are
satisfied. The MIL must also illuminate when the vehicle's ignition is
in the ``key-on'' position before engine starting or cranking and
extinguish after engine starting if no malfunction has previously been
detected. If a fuel system or engine misfire malfunction has previously
been detected, the MIL may be extinguished if the malfunction does not
reoccur during three subsequent sequential trips during which similar
conditions are encountered and no new malfunctions have been detected.
Similar conditions are defined as engine speed within 375 rpm, engine
load within 20 percent, and engine warm-up status equivalent to that
under which the malfunction was first detected. If any malfunction
other than a fuel system or engine misfire malfunction has been
detected, the MIL may be extinguished if the malfunction does not
reoccur during three subsequent sequential trips during which the
monitoring system responsible for illuminating the MIL functions
without detecting the malfunction, and no new malfunctions have been
detected. Upon Administrator approval, statistical MIL illumination
protocols may be employed, provided they result in comparable
timeliness in detecting a malfunction and evaluating system
performance, i.e., three to six driving cycles would be considered
acceptable.
    (2) Drive cycle or driving cycle, in the context of this section
Sec.  86.010-17, the definition for drive cycle or driving cycle given
in Sec.  86.010-2 is enhanced. A drive cycle means an OBD trip that
consists of engine startup and engine shutoff and includes the period
of engine off time up to the next engine startup. For vehicles that
employ engine shutoff strategies (e.g., engine shutoff at idle), the
manufacturer may use an alternative definition for drive cycle (e.g.,
key-on followed by key-off). Any alternative definition must be based
on equivalence to engine startup and engine shutoff signaling the
beginning and ending of a single driving event for a conventional
vehicle. For applications that span 14,000 pounds GVWR, the
manufacturer may use the drive cycle definition of Sec.  86.010-18 in
lieu of the definition in this paragraph.
    (e), (f), (g), and (h)(1)(i) through (h)(1)(iv) [Reserved]. For
guidance see Sec.  86.005-17.
    (h)(1)(v) [Reserved]. For guidance see Sec.  86.007-17.
    (h)(1)(vi) through (h)(3) [Reserved]. For guidance see Sec.
86.005-17.
    (i) and (j) [Reserved]. For guidance see Sec.  86.007-17.
    (k) [Reserved.]
    7. Section 86.010-18 is added to Subpart A to read as follows:

Sec.  86.010-18  On-board Diagnostics for engines used in applications
greater than 14,000 pounds GVWR.

    (a) General. According to the implementation schedule shown in
paragraph (o) of this section, heavy-duty engines intended for use in a
heavy-duty vehicle weighing more than 14,000 pounds GVWR must be
equipped with an on-board diagnostic (OBD) system capable of monitoring
all emission-related engine systems or components during the life of
the engine. The OBD system is required to detect all malfunctions
specified in paragraphs (g), (h), and (i) of this section although the
OBD system is not required to use a unique monitor to detect each of
those malfunctions.
    (1) When the OBD system detects a malfunction, it must store a
pending, a MIL-on, or a previous-MIL-on diagnostic trouble code (DTC)
in the onboard computer's memory. A malfunction indicator light (MIL)
must also be activated as specified in paragraph (b) of this section.
    (2) The OBD system must be equipped with a data link connector to
provide access to the stored DTCs as specified in paragraph (k)(2) of
this section.
    (3) The OBD system cannot be programmed or otherwise designed to
deactivate based on age and/or mileage. This requirement does not alter
existing law and enforcement practice regarding a manufacturer's
liability for an engine beyond its regulatory useful life, except where
an engine has been programmed or otherwise designed so that an OBD
system deactivates based on age and/or mileage of the engine.
    (4) Drive cycle or driving cycle, in the context of this section,
the definition for drive cycle or driving cycle given in Sec.  86.010-2
is enhanced. A drive cycle means an OBD trip that meets any of the
conditions of paragraphs (a)(4)(i) through (a)(4)(iv) of this section.
Further, for OBD monitors that run during engine-off conditions, the
period of engine-off time following engine shutoff and up to the next
engine start may be considered part of the drive cycle for the
conditions of paragraphs (a)(4)(i) and (a)(4)(iv) of this section. For
engines/vehicles that employ engine shutoff OBD monitoring strategies
that do not require the vehicle operator to restart the engine to
continue vehicle operation (e.g., a hybrid bus with engine shutoff at
idle), the manufacturer may use an alternative definition for drive
cycle (e.g., key-on followed by key-off). Any alternative definition
must be based on equivalence to engine startup and engine shutoff
signaling the beginning and ending of a single driving event for a
conventional vehicle. For engines that are not likely to be routinely
operated for long continuous periods of time, a manufacturer may also
request approval to use an alternative definition for drive cycle
(e.g., solely based on engine start and engine shutoff without regard
to four hours of continuous engine-on time). Administrator approval of
the alternative definition will be based on manufacturer-submitted data
and/or information demonstrating the typical usage, operating habits,
and/or driving patterns of these vehicles.
    (i) Begins with engine start and ends with engine shutoff;

    (ii) Begins with engine start and ends after four hours of
continuous engine-on operation;
    (iii) Begins at the end of the previous four hours of continuous
engine-on operation and ends after four hours of continuous engine-on
operation; or
    (iv) Begins at the end of the previous four hours of continuous
engine-on operation and ends with engine shutoff.
    (b) Malfunction indicator light (MIL) and Diagnostic Trouble Codes
(DTC). The OBD system must incorporate a malfunction indicator light
(MIL) or equivalent and must store specific types of diagnostic trouble
codes (DTC).
    (1) MIL specifications.
    (i) [Reserved.]
    (ii) The OBD system must activate the MIL when the ignition is in
the key-on/engine-off position before engine cranking to indicate that
the MIL is functional. The MIL shall be activated continuously during
this functional check for a minimum of 5 seconds. During this MIL key-
on functional check, the data stream value (see paragraph (k)(4)(ii) of
this section) for MIL status must indicate ``commanded off'' unless the
OBD system has detected a malfunction and has stored a MIL-on DTC. This
MIL key-on functional check is not required during vehicle operation in
the key-on/engine-off position subsequent to the initial engine
cranking of an ignition cycle (e.g., due to an engine stall or other
non-commanded engine shutoff).
    (iii) As an option, the MIL may be used to indicate readiness
status (see paragraph (k)(4)(i) of this section) in a standardized
format in the key-on/engine-off position.
    (iv) A manufacturer may also use the MIL to indicate which, if any,
DTCs are currently stored (e.g., to ``blink'' the stored DTCs). Such
use must not activate unintentionally during routine driver operation.
    (v) [Reserved.]
    (2) MIL activation and DTC storage protocol.
    (i) Within 10 seconds of detecting a potential malfunction, the OBD
system must store a pending DTC that identifies the potential
malfunction.
    (ii) If the potential malfunction is again detected before the end
of the next drive cycle during which monitoring occurs (i.e., the
potential malfunction has been confirmed as a malfunction), then within
10 seconds of such detection the OBD system must activate the MIL
continuously and store a MIL-on DTC. If the potential malfunction is
not detected before the end of the next drive cycle during which
monitoring occurs (i.e., there is no indication of the malfunction at
any time during the drive cycle), the corresponding pending DTC should
be erased at the end of the drive cycle. Similarly, if a malfunction is
detected for the first time and confirmed on a given drive cycle
without need for further evaluation, then within 10 seconds of such
detection the OBD system must activate the MIL continuously and store a
MIL-on DTC.
    (iii) A manufacturer may request Administrator approval to employ
alternative statistical MIL activation and DTC storage protocols to
those specified in paragraphs (b)(2)(i) and (b)(2)(ii) of this section.
Approval will depend upon the manufacturer providing data and/or
engineering evaluations that demonstrate that the alternative protocols
can evaluate system performance and detect malfunctions in a manner
that is equally effective and timely. Strategies requiring on average
more than six drive cycles for MIL activation will not be accepted.
    (iv) The OBD system must store a ``freeze frame'' of the operating
conditions (as defined in paragraph (k)(4)(iii) of this section)
present upon detecting a malfunction or a potential malfunction. In the
event that a pending DTC has matured to a MIL-on DTC, the manufacturer
shall either retain the currently stored freeze frame conditions or
replace the stored freeze frame with freeze frame conditions regarding
the MIL-on DTC. Any freeze frame stored in conjunction with any pending
DTC or MIL-on DTC should be erased upon erasure of the corresponding
DTC.
    (v) If the engine enters a limp-home mode of operation that can
affect emissions or the performance of the OBD system, or in the event
of a malfunction of an onboard computer(s) itself that can affect the
performance of the OBD system, the OBD system must activate the MIL and
store a MIL-on DTC within 10 seconds to inform the vehicle operator. If
the limp-home mode of operation is recoverable (i.e., operation
automatically returns to normal at the beginning of the following
ignition cycle), the OBD system may wait to activate the MIL and store
the MIL-on DTC if the limp-home mode of operation is again entered
before the end of the next ignition cycle rather than activating the
MIL within 10 seconds on the first drive cycle during which the limp-
home mode of operation is entered.
    (vi) Before the end of an ignition cycle, the OBD system must store
a permanent DTC(s) that corresponds to any stored MIL-on DTC(s).
    (3) MIL deactivation and DTC erasure protocol.
    (i) Deactivating the MIL. Except as otherwise provided for in
paragraph (g)(6)(iv)(B) of this section for empty reductant tanks, and
paragraphs (h)(1)(iv)(F), (h)(2)(viii), and (h)(7)(iv)(B) of this
section for gasoline fuel system, misfire, and evaporative system
malfunctions, once the MIL has been activated, it may be deactivated
after three subsequent sequential drive cycles during which the
monitoring system responsible for activating the MIL functions and the
previously detected malfunction is no longer present and provided no
other malfunction has been detected that would independently activate
the MIL according to the requirements outlined in paragraph (b)(2) of
this section.
    (ii) Erasing a MIL-on DTC. The OBD system may erase a MIL-on DTC if
the identified malfunction has not again been detected in at least 40
engine warm up cycles and the MIL is presently not activated for that
malfunction. The OBD system may also erase a MIL-on DTC upon
deactivating the MIL according to paragraph (b)(3)(i) of this section
provided a previous-MIL-on DTC is stored upon erasure of the MIL-on
DTC. The OBD system may erase a previous-MIL-on DTC if the identified
malfunction has not again been detected in at least 40 engine warm up
cycles and the MIL is presently not activated for that malfunction.
    (iii) Erasing a permanent DTC. The OBD system can erase a permanent
DTC only if either of the following conditions occur:
    (A) The OBD system itself determines that the malfunction that
caused the corresponding MIL-on DTC to be stored is no longer present
and is not commanding activation of the MIL, concurrent with the
requirements of paragraph (b)(3)(i) of this section.
    (B) Subsequent to erasing the DTC information from the on-board
computer (i.e., through the use of a scan tool or a battery
disconnect), the OBD monitor for the malfunction that caused the
permanent DTC to be stored has executed the minimum number of
monitoring events necessary for MIL activation and has determined that
the malfunction is no longer present.
    (4) Exceptions to MIL and DTC requirements.
    (i) If a limp-home mode of operation causes an overt indication
(e.g., activation of a red engine shut-down warning light) such that
the driver is certain to respond and have the problem corrected, a
manufacturer may choose not to activate the MIL as required by
paragraph (b)(2)(v) of this section. Additionally, if an auxiliary
emission control device has been properly

activated as approved by the Administrator, a manufacturer may choose
not to activate the MIL.
    (ii) For gasoline engines, a manufacturer may choose to meet the
MIL and DTC requirements in Sec.  86.010-17 in lieu of meeting the
requirements of paragraph (b) of Sec.  86.010-18.
    (a) Monitoring conditions. The OBD system must monitor and detect
the malfunctions specified in paragraphs (g), (h), and (i) of this
section under the following general monitoring conditions. The more
specific monitoring conditions of paragraph (d) of this section are
sometimes required according to the provisions of paragraphs (g), (h),
and (i) of this section.
    (1) As specifically provided for in paragraphs (g), (h), and (i) of
this section, the monitoring conditions for detecting malfunctions must
be technically necessary to ensure robust detection of malfunctions
(e.g., avoid false passes and false indications of malfunctions);
designed to ensure monitoring will occur under conditions that may
reasonably be expected to be encountered in normal vehicle operation
and normal vehicle use; and, designed to ensure monitoring will occur
during the FTP transient test cycle contained in Appendix I paragraph
(f), of this part, or similar drive cycle as approved by the
Administrator.
    (2) Monitoring must occur at least once per drive cycle in which
the monitoring conditions are met.
    (3) Manufacturers may request approval to define monitoring
conditions that are not encountered during the FTP cycle as required in
paragraph (c)(1) of this section. In evaluating the manufacturer's
request, the Administrator will consider the degree to which the
requirement to run during the FTP transient cycle restricts monitoring
during in-use operation, the technical necessity for defining
monitoring conditions that are not encountered during the FTP cycle,
data and/or an engineering evaluation submitted by the manufacturer
that demonstrate that the component/system does not normally function
during the FTP, whether monitoring is otherwise not feasible during the
FTP cycle, and/or the ability of the manufacturer to demonstrate that
the monitoring conditions satisfy the minimum acceptable in-use monitor
performance ratio requirement as defined in paragraph (d) of this
section.
    (d) In-use performance tracking. As specifically required in
paragraphs (g), (h), and (i) of this section, the OBD system must
monitor and detect the malfunctions specified in paragraphs (g), (h),
and (i) of this section according to the criteria of this paragraph
(d). The OBD system is not required to track and report in-use
performance for monitors other than those specifically identified in
paragraph (d)(1) of this section.
    (1) The manufacturer must implement software algorithms in the OBD
system to individually track and report the in-use performance of the
following monitors, if equipped, in the standardized format specified
in paragraph (e) of this section: NMHC converting catalyst (paragraph
(g)(5) of this section); NOX converting catalyst (paragraph
(g)(6) of this section); gasoline catalyst (paragraph (h)(6) of this
section); exhaust gas sensor (paragraph (g)(9) or (h)(8) of this
section); evaporative system (paragraph (h)(7) of this section); EGR
system (paragraph (g)(3) or (h)(3) of this section); VVT system
(paragraph (g)(10) or (h)(9) of this section); secondary air system
(paragraph (h)(5) of this section); DPF system (paragraph (g)(8) of
this section); boost pressure control system (paragraph (g)(4) of this
section); and, NOX adsorber system (paragraph (g)(7) of this
section).
    (i) The manufacturer shall not use the calculated ratio specified
in paragraph (d)(2) of this section or any other indication of monitor
frequency as a monitoring condition for a monitor (e.g., using a low
ratio to enable more frequent monitoring through diagnostic executive
priority or modification of other monitoring conditions, or using a
high ratio to enable less frequent monitoring).
    (ii) [Reserved.]
    (2) In-use performance ratio definition. For monitors required to
meet the requirements of paragraph (d) of this section, the performance
ratio must be calculated in accordance with the specifications of this
paragraph (d)(2).
    (i) The numerator of the performance ratio is defined as the number
of times a vehicle has been operated such that all monitoring
conditions have been encountered that are necessary for the specific
monitor to detect a malfunction.
    (ii) The denominator is defined as the number of times a vehicle
has been operated in accordance with the provisions of paragraph (d)(4)
of this section.
    (iii) The performance ratio is defined as the numerator divided by
the denominator.
    (3) Specifications for incrementing the numerator.
    (i) Except as provided for in paragraph (d)(3)(v) of this paragraph
(d)(3), the numerator, when incremented, must be incremented by an
integer of one. The numerator shall not be incremented more than once
per drive cycle.
    (ii) The numerator for a specific monitor must be incremented
within 10 seconds if and only if the following criteria are satisfied
on a single drive cycle:
    (A) Every monitoring condition has been satisfied that is necessary
for the specific monitor to detect a malfunction and store a pending
DTC, including applicable enable criteria, presence or absence of
related DTCs, sufficient length of monitoring time, and diagnostic
executive priority assignments (e.g., diagnostic ``A'' must execute
prior to diagnostic ``B''). For the purpose of incrementing the
numerator, satisfying all the monitoring conditions necessary for a
monitor to determine that the monitor is not malfunctioning shall not,
by itself, be sufficient to meet this criteria.
    (B) For monitors that require multiple stages or events in a single
drive cycle to detect a malfunction, every monitoring condition
necessary for all events to complete must be satisfied.
    (C) For monitors that require intrusive operation of components to
detect a malfunction, a manufacturer must request approval of the
strategy used to determine that, had a malfunction been present, the
monitor would have detected the malfunction. Administrator approval of
the request will be based on the equivalence of the strategy to actual
intrusive operation and the ability of the strategy to determine
accurately if every monitoring condition was satisfied that was
necessary for the intrusive event to occur.
    (D) For the secondary air system monitor, the criteria in
paragraphs (d)(3)(ii)(A) through (d)(3)(ii)(C) of this section are
satisfied during normal operation of the secondary air system.
Monitoring during intrusive operation of the secondary air system later
in the same drive cycle for the sole purpose of monitoring shall not,
by itself, be sufficient to meet these criteria.
    (iii) For monitors that can generate results in a ``gray zone'' or
``non-detection zone'' (i.e., monitor results that indicate neither a
properly operating system nor a malfunctioning system) or in a ``non-
decision zone'' (e.g., monitors that increment and decrement counters
until a pass or fail threshold is reached), the numerator, in general,
shall not be incremented when the monitor indicates a result in the
``non-detection zone'' or prior to the monitor reaching a complete
decision. When necessary, the Administrator will consider data and/or
engineering analyses submitted by the manufacturer

demonstrating the expected frequency of results in the ``non-detection
zone'' and the ability of the monitor to determine accurately, had an
actual malfunction been present, whether or not the monitor would have
detected a malfunction instead of a result in the ``non-detection
zone.''
    (iv) For monitors that run or complete their evaluation with the
engine off, the numerator must be incremented either within 10 seconds
of the monitor completing its evaluation in the engine off state, or
during the first 10 seconds of engine start on the subsequent drive
cycle.
    (v) Manufacturers that use alternative statistical MIL activation
protocols as allowed in paragraph (b)(2)(iii) of this section for any
of the monitors requiring a numerator, are required to increment the
numerator(s) appropriately. The manufacturer may be required to provide
supporting data and/or engineering analyses demonstrating both the
equivalence of their incrementing approach to the incrementing
specified in this paragraph (d)(3) for monitors using the standard MIL
activation protocol.
    (4) Specifications for incrementing the denominator.
    (i) The denominator, when incremented, must be incremented by an
integer of one. The denominator shall not be incremented more than once
per drive cycle.
    (ii) The denominator for each monitor must be incremented within 10
seconds if and only if the following criteria are satisfied on a single
drive cycle:
    (A) Cumulative time since the start of the drive cycle is greater
than or equal to 600 seconds while at an elevation of less than 8,000
feet (2,400 meters) above sea level and at an ambient temperature of
greater than or equal to 20 degrees Fahrenheit (-7 C);
    (B) Cumulative gasoline engine operation at or above 25 miles per
hour or diesel engine operation at or above 15% calculated load, either
of which occurs for greater than or equal to 300 seconds while at an
elevation of less than 8,000 feet (2,400 meters) above sea level and at
an ambient temperature of greater than or equal to 20 degrees
Fahrenheit (-7 C); and
    (C) Continuous vehicle operation at idle (e.g., accelerator pedal
released by driver and vehicle speed less than or equal to one mile per
hour) for greater than or equal to 30 seconds while at an elevation of
less than 8,000 feet (2,400 meters) above sea level and at an ambient
temperature of greater than or equal to 20 degrees Fahrenheit (-7 C).
    (iii) In addition to the requirements of paragraph (d)(4)(ii) of
this section, the evaporative system monitor denominator(s) may be
incremented if and only if:
    (A) Cumulative time since the start of the drive cycle is greater
than or equal to 600 seconds while at an ambient temperature of greater
than or equal to 40 degrees Fahrenheit (4 C) but less than or equal to
95 degrees Fahrenheit (35 C); and,
    (B) Engine cold start occurs with the engine coolant temperature
greater than or equal to 40 degrees Fahrenheit (4 C) but less than or
equal to 95 degrees Fahrenheit (35 C) and less than or equal to 12
degrees Fahrenheit (7 C) higher than the ambient temperature.
    (iv) In addition to the requirements of paragraph (d)(4)(ii) of
this section, the denominator(s) for the following monitors may be
incremented if and only if the component or strategy is commanded
``on'' for a time greater than or equal to 10 seconds. For purposes of
determining this commanded ``on'' time, the OBD system shall not
include time during intrusive operation of any of the components or
strategies that occurs later in the same drive cycle for the sole
purpose of monitoring.
    (A) Secondary air system (paragraph (h)(5) of this section).
    (B) Cold start emission reduction strategy (paragraph (h)(4) of
this section).
    (C) Components or systems that operate only at engine start-up
(e.g., glow plugs, intake air heaters) and are subject to monitoring
under ``other emission control systems'' (paragraph (i)(4) of this
section) or comprehensive component output components (paragraph
(i)(3)(iii) of this section).
    (v) In addition to the requirements of paragraph (d)(4)(ii) of this
section, the denominator(s) for the following monitors of output
components (except those operated only at engine start-up and subject
to the requirements of paragraph (d)(4)(iv) of this section, may be
incremented if and only if the component is commanded to function
(e.g., commanded ``on'', ``opened'', ``closed'', ``locked'') on two or
more occasions during the drive cycle or for a time greater than or
equal to 10 seconds, whichever occurs first:
    (A) Variable valve timing and/or control system (paragraph (g)(10)
or (h)(9) of this section).
    (B) ``Other emission control systems'' (paragraph (i)(4) of this
section).
    (C) Comprehensive component output component (paragraph (i)(3) of
this section) (e.g., turbocharger waste-gates, variable length manifold
runners).
    (vi) For monitors of the following components, the manufacturer may
use alternative or additional criteria for incrementing the denominator
to that set forth in paragraph (d)(4)(ii) of this section. To do so,
the alternative criteria must be based on equivalence to the criteria
of paragraph (d)(4)(ii) of this section in measuring the frequency of
monitor operation relative to the amount of engine operation:
    (A) Engine cooling system input components (paragraph (i)(1) of
this section).
    (B) ``Other emission control systems'' (paragraph (i)(4) of this
section).
    (C) Comprehensive component input components that require extended
monitoring evaluation (paragraph (i)(3) of this section) (e.g., stuck
fuel level sensor rationality).
    (vii) For monitors of the following components or other emission
controls that experience infrequent regeneration events, the
manufacturer may use alternative or additional criteria for
incrementing the denominator to that set forth in paragraph (d)(4)(ii)
of this section. To do so, the alternative criteria must be based on
equivalence to the criteria of paragraph (d)(4)(ii) of this section in
measuring the frequency of monitor operation relative to the amount of
engine operation:
    (A) Oxidation catalyst (paragraph (g)(5) of this section).
    (B) DPF (paragraph (g)(8) of this section).
    (viii) For hybrids that employ alternative engine start hardware or
strategies (e.g., integrated starter and generators), or alternative
fuel vehicles (e.g. dedicated, bi-fuel, or dual-fuel applications), the
manufacturer may use alternative criteria for incrementing the
denominator to that set forth in paragraph (d)(4)(ii) of this section.
In general, the Administrator will not approve alternative criteria for
those hybrids that employ engine shut off only at or near idle and/or
vehicle stop conditions. To use alternative criteria, the alternative
criteria must be based on the equivalence to the criteria of paragraph
(d)(4)(ii) of this section in measuring the amount of vehicle operation
relative to the measure of conventional vehicle operation.
    (5) Disablement of numerators and denominators.
    (i) Within 10 seconds of detecting a malfunction (i.e. a pending or
a MIL-on DTC has been stored) that disables a monitor for which the
monitoring conditions in paragraph (d) of this section must be met, the
OBD system must stop incrementing the numerator and denominator for any
monitor that may be disabled as a consequence of the detected
malfunction. Within 10 seconds of the time at which the malfunction is
no longer being detected

(e.g., the pending DTC is erased through OBD system self-clearing or
through a scan tool command), incrementing of all applicable numerators
and denominators must resume.
    (ii) Within 10 seconds of the start of a power take-off unit (e.g.,
dump bed, snow plow blade, or aerial bucket, etc.) that disables a
monitor for which the monitoring conditions in paragraph (d) of this
section must be met, the OBD system must stop incrementing the
numerator and denominator for any monitor that may be disabled as a
consequence of power take-off operation. Within 10 seconds of the time
at which the power take-off operation ends, incrementing of all
applicable numerators and denominators must resume.
    (iii) Within 10 seconds of detecting a malfunction (i.e., a pending
or a MIL-on DTC has been stored) of any component used to determine if
the criteria of paragraphs (d)(4)(ii) and (d)(4)(iii) of this section
are satisfied, the OBD system must stop incrementing all applicable
numerators and denominators. Within 10 seconds of the time at which the
malfunction is no longer being detected (e.g., the pending DTC is
erased through OBD system self-clearing or through a scan tool
command), incrementing of all applicable numerators and denominators
must resume.
    (e) Standardized tracking and reporting of in-use monitor
performance.
    (1) General. For monitors required to track and report in-use
monitor performance according to paragraph (d) of this section, the
performance data must be tracked and reported in accordance with the
specifications in paragraphs (d)(2), (e), and (k)(5) of this section.
The OBD system must separately report an in-use monitor performance
numerator and denominator for each of the following components:
    (i) For diesel engines, NMHC catalyst bank 1, NMHC catalyst bank 2,
NOX catalyst bank 1, NOX catalyst bank 2, exhaust
gas sensor bank 1, exhaust gas sensor bank 2, EGR/VVT system, DPF,
boost pressure control system, and NOX adsorber. The OBD
system must also report a general denominator and an ignition cycle
counter in the standardized format specified in paragraphs (e)(5),
(e)(6), and (k)(5) of this section.
    (ii) For gasoline engines, catalyst bank 1, catalyst bank 2,
exhaust gas sensor bank 1, exhaust gas sensor bank 2, evaporative leak
detection system, EGR/VVT system, and secondary air system. The OBD
system must also report a general denominator and an ignition cycle
counter in the standardized format specified in paragraphs (e)(5),
(e)(6), and (k)(5) of this section.
    (iii) For specific components or systems that have multiple
monitors that are required to be reported under paragraphs (g) and (h)
of this section (e.g., exhaust gas sensor bank 1 may have multiple
monitors for sensor response or other sensor characteristics), the OBD
system must separately track numerators and denominators for each of
the specific monitors and report only the corresponding numerator and
denominator for the specific monitor that has the lowest numerical
ratio. If two or more specific monitors have identical ratios, the
corresponding numerator and denominator for the specific monitor that
has the highest denominator must be reported for the specific
component.
    (2) Numerator.
    (i) The OBD system must report a separate numerator for each of the
applicable components listed in paragraph (e)(1) of this section.
    (ii) The numerator(s) must be reported in accordance with the
specifications in paragraph (k)(5)(ii) of this section.
    (3) Denominator.
    (i) The OBD system must report a separate denominator for each of
the applicable components listed in paragraph (e)(1) of this section.
    (ii) The denominator(s) must be reported in accordance with the
specifications in paragraph (k)(5)(ii) of this section.
    (4) Monitor performance ratio. For purposes of determining which
corresponding numerator and denominator to report as required in
paragraph (e)(1)(iii) of this section, the ratio must be calculated in
accordance with the specifications in paragraph (k)(5)(iii) of this
section.
    (5) Ignition cycle counter.
    (i) The ignition cycle counter is defined as a counter that
indicates the number of ignition cycles a vehicle has experienced
according to the specifications of paragraph (e)(5)(ii)(B) of this
section. The ignition cycle counter must be reported in accordance with
the specifications in paragraph (k)(5)(ii) of this section.
    (ii) The ignition cycle counter must be incremented as follows:
    (A) The ignition cycle counter, when incremented, must be
incremented by an integer of one. The ignition cycle counter shall not
be incremented more than once per ignition cycle.
    (B) The ignition cycle counter must be incremented within 10
seconds if and only if the engine exceeds an engine speed of 50 to 150
rpm below the normal, warmed-up idle speed (as determined in the drive
position for engines paired with an automatic transmission) for at
least two seconds plus or minus one second.
    (iii) Within 10 seconds of detecting a malfunction (i.e., a pending
or a MIL-on DTC has been stored) of any component used to determine if
the criteria in paragraph (e)(5)(ii)(B) of this section are satisfied
(i.e., engine speed or time of operation), the OBD system must stop
incrementing the ignition cycle counter. Incrementing of the ignition
cycle counter shall not be stopped for any other condition. Within 10
seconds of the time at which the malfunction is no longer being
detected (e.g., the pending DTC is erased through OBD system self-
clearing or through a scan tool command), incrementing of the ignition
cycle counter must resume.
    (6) General denominator.
    (i) The general denominator is defined as a measure of the number
of times an engine has been operated according to the specifications of
paragraph (e)(6)(ii)(B) of this section. The general denominator must
be reported in accordance with the specifications in paragraph
(k)(5)(ii) of this section.
    (ii) The general denominator must be incremented as follows:
    (A) The general denominator, when incremented, must be incremented
by an integer of one. The general denominator shall not be incremented
more than once per drive cycle.
    (B) The general denominator must be incremented within 10 seconds
if and only if the criteria identified in paragraph (d)(4)(ii) of this
section are satisfied on a single drive cycle.
    (C) Within 10 seconds of detecting a malfunction (i.e., a pending
or a MIL-on DTC has been stored) of any component used to determine if
the criteria in paragraph (d)(4)(ii) of this section are satisfied
(i.e., vehicle speed/load, ambient temperature, elevation, idle
operation, or time of operation), the OBD system must stop incrementing
the general denominator. Incrementing of the general denominator shall
not be stopped for any other condition (e.g., the disablement criteria
in paragraphs (d)(5)(i) and (d)(5)(ii) of this section shall not
disable the general denominator). Within 10 seconds of the time at
which the malfunction is no longer being detected (e.g., the pending
DTC is erased through OBD system self-clearing or through a scan tool
command), incrementing of the general denominator must resume.
    (f) Malfunction criteria determination.
    (1) In determining the malfunction criteria for the diesel engine
monitors required under paragraphs (g) and (i) of

this section that are required to indicate a malfunction before
emissions exceed an emission threshold based on any applicable
standard, the manufacturer must:
    (i) Use the emission test cycle and standard (i.e., the transient
FTP or the supplemental emissions test (SET)) determined by the
manufacturer to be more stringent (i.e., to result in higher emissions
with the same level of monitored component malfunction). The
manufacturer must use data and/or engineering analysis to determine the
test cycle and standard that is more stringent.
    (ii) Identify in the certification documentation required under
paragraph (m) of this section, the test cycle and standard determined
by the manufacturer to be the most stringent for each applicable
monitor.
    (iii) If the Administrator reasonably believes that a manufacturer
has determined incorrectly the test cycle and standard that is most
stringent, the manufacturer must be able to provide emission data and/
or engineering analysis supporting their choice of test cycle and
standard.
    (2) On engines equipped with emission controls that experience
infrequent regeneration events, a manufacturer must adjust the emission
test results that are used to determine the malfunction criteria for
monitors that are required to indicate a malfunction before emissions
exceed a certain emission threshold. For each such monitor, the
manufacturer must adjust the emission result as done in accordance with
the provisions of section 86.004-28(i) with the component for which the
malfunction criteria are being established having been deteriorated to
the malfunction threshold. The adjusted emission value must be used for
purposes of determining whether or not the applicable emission
threshold is exceeded.
    (i) For purposes of this paragraph (f)(2) of this section,
regeneration means an event, by design, during which emissions levels
change while the emission control performance is being restored.
    (ii) For purposes of this paragraph (f)(2) of this section,
infrequent means having an expected frequency of less than once per
transient FTP cycle.
    (3) For gasoline engines, rather than meeting the malfunction
criteria specified under paragraphs (h) and (i) of this section, the
manufacturer may request approval to use an OBD system certified to the
requirements of Sec.  86.010-17. To do so, the manufacturer must
demonstrate use of good engineering judgment in determining equivalent
malfunction detection criteria to those required in this section.
    (g) OBD monitoring requirements for diesel-fueled/compression-
ignition engines. The following table shows the thresholds at which
point certain components or systems, as specified in this paragraph
(g), are considered malfunctioning.

Table 1.--OBD Emissions Thresholds for Diesel-Fueled/Compression-Ignition Engines Meant for Placement in Applications Greater Than 14,000 Pounds GVWR (g/
                                                                         bhp-hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Component                   Sec.   86.010-18 reference               NMHC                   CO                    NOX               PM
--------------------------------------------------------------------------------------------------------------------------------------------------------
NMHC catalyst system................  (g)(5)............................  2.5x.................  ....................  ....................  ...........
NOX aftertreatment system...........  (g)(6), (g)(7)....................  .....................  ....................  +0.3................  ...........
Diesel particulate filter (DPF)       (g)(8)............................  2.5x.................  ....................  ....................   0.05/+0.04
 system.
Air-fuel ratio sensors upstream of    (g)(9)............................  2.5x.................  2.5x................  +0.3................   0.03/+0.02
 aftertreatment devices.
Air-fuel ratio sensors downstream of  (g)(9)............................  2.5x.................  ....................  +0.3................   0.05/+0.04
 aftertreatment devices.
NOX sensors.........................  (g)(9)............................  .....................  ....................  +0.3................   0.05/+0.04
``Other monitors'' with emissions     (g)(1), (g)(3), (g)(4), (g)(10)...  2.5x.................  2.5x................  +0.3................  0.03/+0.02
 thresholds.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: FEL=Family Emissions Limit; 2.5x std means a multiple of 2.5 times the applicable emissions standard; +0.3 means the standard or FEL plus 0.3;
  0.05/+0.04 means an absolute level of 0.05 or an additive level of the standard or FEL plus 0.04, whilchever level is higher; these emissions
  thresholds apply to the monitoring requirements of paragraph (g) of this section 86.010-18.

    (1) Fuel system monitoring.
    (i) General. The OBD system must monitor the fuel delivery system
to verify that it is functioning properly. The individual electronic
components (e.g., actuators, valves, sensors, pumps) that are used in
the fuel system and are not specifically addressed in this paragraph
(g)(1) must be monitored in accordance with the requirements of
paragraph (i)(3) of this section.
    (ii) Fuel system malfunction criteria.
    (A) Fuel system pressure control. The OBD system must monitor the
fuel system's ability to control to the desired fuel pressure. This
monitoring must be done continuously unless new hardware has to be
added, in which case the monitoring must be done at least once per
drive cycle. The OBD system must detect a malfunction of the fuel
system's pressure control system when the pressure control system is
unable to maintain an engine's emissions at or below the emissions
thresholds for ``other monitors'' as shown in Table 1 of this paragraph
(g). For engines in which no failure or deterioration of the fuel
system pressure control could result in an engine's emissions exceeding
the applicable emissions thresholds, the OBD system must detect a
malfunction when the system has reached its control limits such that
the commanded fuel system pressure cannot be delivered.
    (B) Fuel system injection quantity. The OBD system must detect a
malfunction of the fuel injection system when the system is unable to
deliver the commanded quantity of fuel necessary to maintain an
engine's emissions at or below the emissions thresholds for ``other
monitors'' as shown in Table 1 of this paragraph (g). For engines in
which no failure or deterioration of the fuel injection quantity could
result in an engine's emissions exceeding the applicable emissions
thresholds, the OBD system must detect a malfunction when the system
has reached its control limits such that the commanded fuel quantity
cannot be delivered.
    (C) Fuel system injection timing. The OBD system must detect a
malfunction of the fuel injection system when the system is unable to
deliver fuel at the proper crank angle/timing (e.g., injection timing
too advanced or too retarded) necessary to maintain an engine's
emissions at or below the emissions thresholds for ``other monitors''
as shown in Table 1 of this paragraph (g). For engines in which no
failure or deterioration of the fuel injection timing could result in
an engine's emissions exceeding the applicable emissions thresholds,
the OBD system must detect a malfunction when the system has reached
its control limits such that the commanded fuel injection timing cannot
be achieved.

    (D) Fuel system feedback control. See paragraph (i)(6) of this
section.
    (iii) Fuel system monitoring conditions.
    (A) The OBD system must monitor continuously for malfunctions
identified in paragraphs (g)(1)(ii)(A) and (g)(1)(ii)(D) of this
section.
    (B) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraphs (g)(1)(ii)(B) and (g)(1)(ii)(C)
in accordance with paragraphs (c) and (d) of this section.
    (iv) Fuel system MIL activation and DTC storage. The MIL must
activate and DTCs must be stored according to the provisions of
paragraph (b) of this section.
    (2) Engine misfire monitoring.
    (i) General. The OBD system must monitor the engine for misfire
causing excess emissions.
    (ii) Engine misfire malfunction criteria. The OBD system must be
capable of detecting misfire occurring in one or more cylinders. To the
extent possible without adding hardware for this specific purpose, the
OBD system must also identify the specific misfiring cylinder. If more
than one cylinder is misfiring continuously, a separate DTC must be
stored indicating that multiple cylinders are misfiring. When
identifying multiple cylinder misfire, the OBD system is not required
to identify individually through separate DTCs each of the continuously
misfiring cylinders.
    (iii) Engine misfire monitoring conditions.
    (A) The OBD system must monitor for engine misfire during engine
idle conditions at least once per drive cycle in which the monitoring
conditions for misfire are met. The manufacturer must be able to
demonstrate via engineering analysis and/or data that the self-defined
monitoring conditions: Are technically necessary to ensure robust
detection of malfunctions (e.g., avoid false passes and false detection
of malfunctions); require no more than 1000 cumulative engine
revolutions; and, do not require any single continuous idle operation
of more than 15 seconds to make a determination that a malfunction is
present (e.g., a decision can be made with data gathered during several
idle operations of 15 seconds or less); or, satisfy the requirements of
paragraph (c) of this section with alternative engine operating
conditions.
    (B) Manufacturers may employ alternative monitoring conditions
(e.g., off-idle) provided the manufacturer is able to demonstrate that
the alternative monitoring ensure equivalent robust detection of
malfunctions and equivalent timeliness in detection of malfunctions.
    (iv) Engine misfire MIL activation and DTC storage. The MIL must
activate and DTCs must be stored according to the provisions of
paragraph (b) of this section.
    (3) EGR system monitoring.
    (i) General. The OBD system must monitor the EGR system on engines
so equipped for low flow rate, high flow rate, and slow response
malfunctions. For engines equipped with EGR coolers (e.g., heat
exchangers), the OBD system must monitor the cooler for insufficient
cooling malfunctions. The individual electronic components (e.g.,
actuators, valves, sensors) that are used in the EGR system must be
monitored in accordance with the comprehensive component requirements
in paragraph (i)(3) of this section.
    (ii) EGR system malfunction criteria.
    (A) EGR low flow. The OBD system must detect a malfunction of the
EGR system prior to a decrease from the manufacturer's specified EGR
flow rate that would cause an engine's emissions to exceed the
emissions thresholds for ``other monitors'' as shown in Table 1 of this
paragraph (g). For engines in which no failure or deterioration of the
EGR system that causes a decrease in flow could result in an engine's
emissions exceeding the applicable emissions thresholds, the OBD system
must detect a malfunction when the system has reached its control
limits such that it cannot increase EGR flow to achieve the commanded
flow rate.
    (B) EGR high flow. The OBD system must detect a malfunction of the
EGR system, including a leaking EGR valve (i.e., exhaust gas flowing
through the valve when the valve is commanded closed) prior to an
increase from the manufacturer's specified EGR flow rate that would
cause an engine's emissions to exceed the emissions thresholds for
``other monitors'' as shown in Table 1 of this paragraph (g). For
engines in which no failure or deterioration of the EGR system that
causes an increase in flow could result in an engine's emissions
exceeding the applicable emissions thresholds, the OBD system must
detect a malfunction when the system has reached its control limits
such that it cannot reduce EGR flow to achieve the commanded flow rate.
    (C) EGR slow response. The OBD system must detect a malfunction of
the EGR system prior to any failure or deterioration in the capability
of the EGR system to achieve the commanded flow rate within a
manufacturer-specified time that would cause an engine's emissions to
exceed the emissions thresholds for ``other monitors'' as shown in
Table 1 of this paragraph (g). The OBD system must monitor both the
capability of the EGR system to respond to a commanded increase in flow
and the capability of the EGR system to respond to a commanded decrease
in flow.
    (D) EGR system feedback control. See paragraph (i)(6) of this
section.
    (E) EGR cooler performance. The OBD system must detect a
malfunction of the EGR cooler prior to a reduction from the
manufacturer's specified cooling performance that would cause an
engine's emissions to exceed the emissions thresholds for ``other
monitors'' as shown in Table 1 of this paragraph (g). For engines in
which no failure or deterioration of the EGR cooler could result in an
engine's emissions exceeding the applicable emissions thresholds, the
OBD system must detect a malfunction when the system has no detectable
amount of EGR cooling.
    (iii) EGR system monitoring conditions.
    (A) The OBD system must monitor continuously for malfunctions
identified in paragraphs (g)(3)(ii)(A), (g)(3)(ii)(B), and
(g)(3)(ii)(D) of this section.
    (B) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraph (g)(3)(ii)(C) in accordance with
paragraphs (c) and (d) of this section, with the exception that
monitoring must occur every time the monitoring conditions are met
during the drive cycle rather than once per drive cycle as required in
paragraph (c)(2) of this section. For purposes of tracking and
reporting as required in paragraph (d)(1) of this section, all monitors
used to detect malfunctions identified in paragraph (g)(3)(ii)(C) of
this section must be tracked separately but reported as a single set of
values as specified in paragraph (e)(1)(iii) of this section.
    (C) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraph (g)(3)(ii)(E) of this section in
accordance with paragraphs (c) and (d) of this section. For purposes of
tracking and reporting as required in paragraph (d)(1) of this section,
all monitors used to detect malfunctions identified in paragraph
(g)(3)(ii)(E) of this section must be tracked separately but reported
as a single set of values as specified in paragraph (e)(1)(iii) of this
section.
    (D) The manufacturer may request Administrator approval to disable
temporarily the EGR system monitor(s) under specific conditions (e.g.,
when freezing may affect performance of the system) provided the
manufacturer is

able to demonstrate via data or engineering analysis that a reliable
monitor cannot be run when these conditions exist.
    (iv) EGR system MIL activation and DTC storage. The MIL must
activate and DTCs must be stored according to the provisions of
paragraph (b) of this section.
    (4) Turbo boost control system monitoring.
    (i) General. The OBD system must monitor the boost pressure control
system (e.g., turbocharger) on engines so equipped for under and over
boost malfunctions. For engines equipped with variable geometry
turbochargers (VGT), the OBD system must monitor the VGT system for
slow response malfunctions. For engines equipped with charge air cooler
systems, the OBD system must monitor the charge air cooler system for
cooling system performance malfunctions. The individual electronic
components (e.g., actuators, valves, sensors) that are used in the
boost pressure control system must be monitored in accordance with the
comprehensive component requirements in paragraph (i)(3) of this
section.
    (ii) Turbo boost control system malfunction criteria.
    (A) Turbo underboost. The OBD system must detect a malfunction of
the boost pressure control system prior to a decrease from the
manufacturer's commanded boost pressure that would cause an engine's
emissions to exceed the emissions thresholds for ``other monitors'' as
shown in Table 1 of this paragraph (g). For engines in which no failure
or deterioration of the boost pressure control system that causes a
decrease in boost could result in an engine's emissions exceeding the
applicable emissions thresholds, the OBD system must detect a
malfunction when the system has reached its control limits such that it
cannot increase boost to achieve the commanded boost pressure.
    (B) Turbo overboost. The OBD system must detect a malfunction of
the boost pressure control system prior to an increase from the
manufacturer's commanded boost pressure that would cause an engine's
emissions to exceed the emissions thresholds for ``other monitors'' as
shown in Table 1 of this paragraph (g). For engines in which no failure
or deterioration of the boost pressure control system that causes an
increase in boost could result in an engine's emissions exceeding the
applicable emissions thresholds, the OBD system must detect a
malfunction when the system has reached its control limits such that it
cannot decrease boost to achieve the commanded boost pressure.
    (C) VGT slow response. The OBD system must detect a malfunction
prior to any failure or deterioration in the capability of the VGT
system to achieve the commanded turbocharger geometry within a
manufacturer-specified time that would cause an engine's emissions to
exceed the emissions thresholds for ``other monitors'' as shown in
Table 1 of this paragraph (g). For engines in which no failure or
deterioration of the VGT system response could result in an engine's
emissions exceeding the applicable emissions thresholds, the OBD system
must detect a malfunction of the VGT system when proper functional
response of the system to computer commands does not occur.
    (D) Turbo boost feedback control. See paragraph (i)(6) of this
section.
    (E) Charge air undercooling. The OBD system must detect a
malfunction of the charge air cooling system prior to a decrease from
the manufacturer's specified cooling rate that would cause an engine's
emissions to exceed the emissions thresholds for ``other monitors'' as
shown in Table 1 of this paragraph (g). For engines in which no failure
or deterioration of the charge air cooling system that causes a
decrease in cooling performance could result in an engine's emissions
exceeding the applicable emissions thresholds, the OBD system must
detect a malfunction when the system has no detectable amount of charge
air cooling.
    (iii) Turbo boost monitoring conditions.
    (A) The OBD system must monitor continuously for malfunctions
identified in paragraphs (g)(4)(ii)(A), (g)(4)(ii)(B), and
(g)(4)(ii)(D) of this section.
    (B) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraph (g)(4)(ii)(C) of this section in
accordance with paragraphs (c) and (d) of this section, with the
exception that monitoring must occur every time the monitoring
conditions are met during the drive cycle rather than once per drive
cycle as required in paragraph (c)(2) of this section. For purposes of
tracking and reporting as required in paragraph (d)(1) of this section,
all monitors used to detect malfunctions identified in paragraph
(g)(4)(ii)(C) of this section must be tracked separately but reported
as a single set of values as specified in paragraph (e)(1)(iii) of this
section.
    (C) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraph (g)(4)(ii)(E) of this section in
accordance with paragraphs (c) and (d) of this section. For purposes of
tracking and reporting as required in paragraph (d)(1) of this section,
all monitors used to detect malfunctions identified in paragraph
(g)(4)(ii)(E) of this section must be tracked separately but reported
as a single set of values as specified in paragraph (e)(1)(iii) of this
section.
    (iv) Turbo boost system MIL activation and DTC storage. The MIL
must activate and DTCs must be stored according to the provisions of
paragraph (b) of this section.
    (5) NMHC converting catalyst monitoring.
    (i) General. The OBD system must monitor the NMHC converting
catalyst(s) for proper NMHC conversion capability. For engines equipped
with catalyzed diesel particulate filter(s) (DPF) that convert NMHC
emissions, the catalyst function of the DPF must be monitored in
accordance with the DPF requirements of paragraph (g)(8) of this
section. For purposes of this paragraph (g)(5), each catalyst that
converts NMHC must be monitored either individually or in combination
with others.
    (ii) NMHC converting catalyst malfunction criteria.
    (A) NMHC converting catalyst conversion efficiency. The OBD system
must detect a catalyst malfunction when the catalyst conversion
capability decreases to the point that NMHC emissions exceed the
emissions thresholds for the NMHC catalyst system as shown in Table 1
of this paragraph (g). If no failure or deterioration of the catalyst
NMHC conversion capability could result in an engine's NMHC emissions
exceeding the applicable emissions thresholds, the OBD system must
detect a malfunction when the catalyst has no detectable amount of NMHC
conversion capability.
    (B) NMHC converting catalyst aftertreatment assistance functions.
For catalysts used to generate an exotherm to assist DPF regeneration,
the OBD system must detect a malfunction when the catalyst is unable to
generate a sufficient exotherm to achieve DPF regeneration. For
catalysts used to generate a feedgas constituency to assist selective
catalytic reduction (SCR) systems (e.g., to increase NO2
concentration upstream of an SCR system), the OBD system must detect a
malfunction when the catalyst is unable to generate the necessary
feedgas constituents for proper SCR system operation. For catalysts
located downstream of a DPF and used to convert NMHC emissions during
DPF regeneration, the OBD system must detect a malfunction when the
catalyst has no detectable amount of NMHC conversion capability.

    (iii) NMHC converting catalyst monitoring conditions. The
manufacturer must define the monitoring conditions for malfunctions
identified in paragraphs (g)(5)(ii)(A) and (g)(5)(ii)(B) of this
section in accordance with paragraphs (c) and (d) of this section. For
purposes of tracking and reporting as required in paragraph (d)(1) of
this section, all monitors used to detect malfunctions identified in
paragraphs (g)(5)(ii)(A) and (g)(5)(ii)(B) of this section must be
tracked separately but reported as a single set of values as specified
in paragraph (e)(1)(iii) of this section.
    (iv) NMHC converting catalyst MIL activation and DTC storage. The
MIL must activate and DTCs must be stored according to the provisions
of paragraph (b) of this section. The monitoring method for the NMHC
converting catalyst(s) must be capable of detecting all instances,
except diagnostic self-clearing, when a catalyst DTC has been erased
but the catalyst has not been replaced (e.g., catalyst over-temperature
histogram approaches are not acceptable).
    (6) Selective catalytic reduction (SCR) and lean NOX catalyst
monitoring.
    (i) General. The OBD system must monitor the SCR and/or the lean
NOX converting catalyst(s) for proper conversion capability.
For engines equipped with SCR systems or other catalyst systems that
use an active/intrusive reductant injection (e.g., active lean
NOX catalysts that use diesel fuel post-injection or in-
exhaust injection), the OBD system must monitor the active/intrusive
reductant injection system for proper performance. The individual
electronic components (e.g., actuators, valves, sensors, heaters,
pumps) in the active/intrusive reductant injection system must be
monitored in accordance with the comprehensive component requirements
in paragraph (i)(3) of this section. For purposes of this paragraph
(g)(6), each catalyst that converts NOX must be monitored
either individually or in combination with others.
    (ii) SCR and lean NOX catalyst malfunction criteria.
    (A) SCR and lean NOX catalyst conversion efficiency. The OBD system
must detect a catalyst malfunction when the catalyst conversion
capability decreases to the point that would cause an engine's
emissions to exceed the emissions thresholds for NOX
aftertreatment systems as shown in Table 1 of this paragraph (g). If no
failure or deterioration of the catalyst NOX conversion
capability could result in an engine's emissions exceeding any of the
applicable emissions thresholds, the OBD system must detect a
malfunction when the catalyst has no detectable amount of
NOX conversion capability.
    (B) SCR and lean NOX catalyst active/intrusive reductant delivery
performance. The OBD system must detect a malfunction prior to any
failure or deterioration of the system to properly regulate reductant
delivery (e.g., urea injection, separate injector fuel injection, post
injection of fuel, air assisted injection/mixing) that would cause an
engine's emissions to exceed any of the applicable emissions thresholds
for NOX aftertreatment systems as shown in Table 1 of this
paragraph (g). If no failure or deterioration of the reductant delivery
system could result in an engine's emissions exceeding any of the
applicable thresholds, the OBD system must detect a malfunction when
the system has reached its control limits such that it is no longer
able to deliver the desired quantity of reductant.
    (C) SCR and lean NOX catalyst active/intrusive reductant quantity.
If the SCR or lean NOX catalyst system uses a reductant
other than the fuel used for the engine, or uses a reservoir/tank for
the reductant that is separate from the fuel tank used for the engine,
the OBD system must detect a malfunction when there is no longer
sufficient reductant available (e.g., the reductant tank is empty).
    (D) SCR and lean NOX catalyst active/intrusive reductant quality.
If the SCR or lean NOX catalyst system uses a reservoir/tank
for the reductant that is separate from the fuel tank used for the
engine, the OBD system must detect a malfunction when an improper
reductant is used in the reductant reservoir/tank (e.g., the reductant
tank is filled with something other than the reductant).
    (E) SCR and lean NOX catalyst active/intrusive reductant feedback
control. See paragraph (i)(6) of this section.
    (iii) SCR and lean NOX catalyst monitoring conditions.
    (A) The manufacturers must define the monitoring conditions for
malfunctions identified in paragraphs (g)(6)(ii)(A) and (g)(6)(ii)(D)
of this section in accordance with paragraphs (c) and (d) of this
section. For purposes of tracking and reporting as required in
paragraph (d)(1) of this section, all monitors used to detect
malfunctions identified in paragraph (g)(6)(ii)(A) of this section must
be tracked separately but reported as a single set of values as
specified in paragraph (e)(1)(iii) of this section.
    (B) The OBD system must monitor continuously for malfunctions
identified in paragraphs (g)(6)(ii)(B), (g)(6)(ii)(C), and
(g)(6)(ii)(E) of this section.
    (iv) SCR and lean NOX catalyst MIL activation and DTC
storage.
    (A) For malfunctions identified in paragraph (g)(6)(ii)(A) of this
section, the MIL must activate and DTCs must be stored according to the
provisions of paragraph (b) of this section.
    (B) For malfunctions identified in paragraphs (g)(6)(ii)(B),
(g)(6)(ii)(C), and (g)(6)(ii)(D) of this section, the manufacturer may
delay activating the MIL if the vehicle is equipped with an alternative
indicator for notifying the vehicle operator of the malfunction. The
alternative indicator must be of sufficient illumination and be located
such that it is readily visible to the vehicle operator under all
lighting conditions. If the vehicle is not equipped with such an
alternative indicator and the OBD MIL activates, the MIL may be
immediately deactivated and the corresponding DTC(s) erased once the
OBD system has verified that the reductant tank has been refilled
properly and the MIL has not been activated for any other malfunction.
The Administrator may approve other strategies that provide equivalent
assurance that a vehicle operator would be promptly notified and that
corrective action would be taken.
    (C) The monitoring method for the SCR and lean NOX
catalyst(s) must be capable of detecting all instances, except
diagnostic self-clearing, when a catalyst DTC(s) has been erased but
the catalyst has not been replaced (e.g., catalyst over-temperature
histogram approaches are not acceptable).
    (7) NOX adsorber system monitoring.
    (i) General. The OBD system must monitor the NOX
adsorber on engines so-equipped for proper performance. For engines
equipped with active/intrusive injection (e.g., in-exhaust fuel and/or
air injection) to achieve desorption of the NOX adsorber,
the OBD system must monitor the active/intrusive injection system for
proper performance. The individual electronic components (e.g.,
injectors, valves, sensors) that are used in the active/intrusive
injection system must be monitored in accordance with the comprehensive
component requirements in paragraph (i)(3) of this section.
    (ii) NOX adsorber system malfunction criteria.
    (A) NOX adsorber system capability. The OBD system must
detect a NOX adsorber malfunction when its capability (i.e.,
its combined adsorption and conversion capability) decreases to

[[Continued on page 3299]]

]

[[pp. 3299-3344]] Control of Air Pollution From New Motor Vehicles and New Motor
Vehicle Engines; Regulations Requiring Onboard Diagnostic Systems on
2010 and Later Heavy-Duty Engines Used in Highway Applications Over
14,000 Pounds; Revisions to Onboard Diagnostic Requirements f[[Page 3299]]

[[Continued from page 3298]]

the point that would cause an engine's NOX emissions to
exceed the emissions thresholds for NOX aftertreatment
systems as shown in Table 1 of this paragraph (g). If no failure or
deterioration of the NOX adsorber capability could result in
an engine's NOX emissions exceeding the applicable emissions
thresholds, the OBD system must detect a malfunction when the system
has no detectable amount of NOX adsorber capability.
    (B) NOX adsorber system active/intrusive reductant
delivery performance. For NOX adsorber systems that use
active/intrusive injection (e.g., in-cylinder post fuel injection, in-
exhaust air-assisted fuel injection) to achieve desorption of the
NOX adsorber, the OBD system must detect a malfunction if
any failure or deterioration of the injection system's ability to
properly regulate injection causes the system to be unable to achieve
desorption of the NOX adsorber.
    (C) NOX adsorber system feedback control. Malfunction
criteria for the NOX adsorber and the NOX
adsorber active/instrusive reductant delivery system are contained in
paragraph (i)(6)of this section.
    (iii) NOX adsorber system monitoring conditions.
    (A) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraph (g)(7)(ii)(A) of this section in
accordance with paragraphs (c) and (d) of this section. For purposes of
tracking and reporting as required in paragraph (d)(1) of this section,
all monitors used to detect malfunctions identified in paragraph
(g)(7)(ii)(A) of this section must be tracked separately but reported
as a single set of values as specified in paragraph (e)(1)(iii) of this
section.
    (B) The OBD system must monitor continuously for malfunctions
identified in paragraphs (g)(7)(ii)(B) and (g)(7)(ii)(C) of this
section.
    (iv) NOX adsorber system MIL activation and DTC storage.
The MIL must activate and DTCs must be stored according to the
provisions of paragraph (b) of this section.
    (8) Diesel particulate filter (DPF) system monitoring.
    (i) General. The OBD system must monitor the DPF on engines so-
equipped for proper performance. For engines equipped with active
regeneration systems that use an active/intrusive injection (e.g., in-
exhaust fuel injection, in-exhaust fuel/air burner), the OBD system
must monitor the active/intrusive injection system for proper
performance. The individual electronic components (e.g., injectors,
valves, sensors) that are used in the active/intrusive injection system
must be monitored in accordance with the comprehensive component
requirements in paragraph (i)(3) of this section.
    (ii) DPF system malfunction criteria.
    (A) DPF filtering performance. The OBD system must detect a
malfunction prior to a decrease in the PM filtering capability of the
DPF (e.g., cracking, melting, etc.) that would cause an engine's PM
emissions to exceed the emissions thresholds for DPF systems as shown
in Table 1 of this paragraph (g). If no failure or deterioration of the
PM filtering performance could result in an engine's PM emissions
exceeding the applicable emissions thresholds, the OBD system must
detect a malfunction when no detectable amount of PM filtering occurs.
    (B) DPF regeneration frequency. The OBD system must detect a
malfunction when the DPF regeneration frequency increases from (i.e.,
occurs more often than) the manufacturer's specified regeneration
frequency to a level such that it would cause an engine's NMHC
emissions to exceed the emissions threshold for DPF systems as shown in
Table 1 of this paragraph (g). If no such regeneration frequency exists
that could cause NMHC emissions to exceed the applicable emission
threshold, the OBD system must detect a malfunction when the DPF
regeneration frequency exceeds the manufacturer's specified design
limits for allowable regeneration frequency.
    (C) DPF incomplete regeneration. The OBD system must detect a
regeneration malfunction when the DPF does not properly regenerate
under manufacturer-defined conditions where regeneration is designed to
occur.
    (D) DPF NMHC conversion. For any DPF that serves to convert NMHC
emissions, the OBD system must detect a malfunction when the NMHC
conversion capability decreases to the point that NMHC emissions exceed
the emissions threshold for DPF systems as shown in Table 1 of this
paragraph (g). If no failure or deterioration of the NMHC conversion
capability could result in NMHC emissions exceeding the applicable
threshold, the OBD system must detect a malfunction when the system has
no detectable amount of NMHC conversion capability.
    (E) DPF missing substrate. The OBD system must detect a malfunction
if either the DPF substrate is completely destroyed, removed, or
missing, or if the DPF assembly has been replaced with a muffler or
straight pipe.
    (F) DPF system active/intrusive injection. For DPF systems that use
active/intrusive injection (e.g., in-cylinder post fuel injection, in-
exhaust air-assisted fuel injection) to achieve regeneration of the
DPF, the OBD system must detect a malfunction if any failure or
deterioration of the injection system's ability to properly regulate
injection causes the system to be unable to achieve regeneration of the
DPF.
    (G) DPF regeneration feedback control. See paragraph (i)(6) of this
section.
    (iii) DPF monitoring conditions. The manufacturer must define the
monitoring conditions for malfunctions identified in paragraph
(g)(8)(ii) of this section in accordance with paragraphs (c) and (d) of
this section, with the exception that monitoring must occur every time
the monitoring conditions are met during the drive cycle rather than
once per drive cycle as required in paragraph (c)(2) of this section.
For purposes of tracking and reporting as required in paragraph (d)(1)
of this section, all monitors used to detect malfunctions identified in
paragraph (g)(8)(ii) of this section must be tracked separately but
reported as a single set of values as specified in paragraph
(e)(1)(iii) of this section.
    (iv) DPF system MIL activation and DTC storage. The MIL must
activate and DTCs must be stored according to the provisions of
paragraph (b) of this section.
    (9) Exhaust gas sensor and sensor heater monitoring.
    (i) General. The OBD system must monitor for proper output signal,
activity, response rate, and any other parameter that can affect
emissions, all exhaust gas sensors (e.g., oxygen, air-fuel ratio,
NOX) used for emission control system feedback (e.g., EGR
control/feedback, SCR control/feedback, NOX adsorber
control/feedback) and/or as a monitoring device. For engines equipped
with heated exhaust gas sensors, the OBD system must monitor the heater
for proper performance.
    (ii) Malfunction criteria for air-fuel ratio sensors located
upstream of aftertreatment devices.
    (A) Sensor performance. The OBD system must detect a malfunction
prior to any failure or deterioration of the sensor voltage,
resistance, impedance, current, response rate, amplitude, offset, or
other characteristic(s) that would cause an engine's emissions to
exceed the emissions thresholds for ``other monitors'' as shown in
Table 1 of this paragraph (g).
    (B) Circuit integrity. The OBD system must detect malfunctions of
the sensor related to a lack of circuit continuity or signal out-of-
range values.
    (C) Feedback function. The OBD system must detect a malfunction of
the

sensor if the emission control system (e.g., EGR, SCR, or
NOX adsorber) is unable to use that sensor as a feedback
input (e.g., causes limp-home or open-loop operation).
    (D) Monitoring function. To the extent feasible, the OBD system
must detect a malfunction of the sensor when the sensor output voltage,
resistance, impedance, current, amplitude, activity, offset, or other
characteristics are no longer sufficient for use as an OBD system
monitoring device (e.g., for catalyst, EGR, SCR, or NOX
adsorber monitoring).
    (iii) Malfunction criteria for air-fuel ratio sensors located
downstream of aftertreatment devices.
    (A) Sensor performance. The OBD system must detect a malfunction
prior to any failure or deterioration of the sensor voltage,
resistance, impedance, current, response rate, amplitude, offset, or
other characteristic(s) that would cause an engine's emissions to
exceed the emissions thresholds for air-fuel ratio sensors downstream
of aftertreatment devices as shown in Table 1 of this paragraph (g).
    (B) Circuit integrity. The OBD system must detect malfunctions of
the sensor related to a lack of circuit continuity or signal out-of-
range values.
    (C) Feedback function. The OBD system must detect a malfunction of
the sensor if the emission control system (e.g., EGR, SCR, or
NOX adsorber) is unable to use that sensor as a feedback
input (e.g., causes limp-home or open-loop operation).
    (D) Monitoring function. To the extent feasible, the OBD system
must detect a malfunction of the sensor when the sensor output voltage,
resistance, impedance, current, amplitude, activity, offset, or other
characteristics are no longer sufficient for use as an OBD system
monitoring device (e.g., for catalyst, EGR, SCR, or NOX
adsorber monitoring).
    (iv) Malfunction criteria for NOX sensors.
    (A) Sensor performance. The OBD system must detect a malfunction
prior to any failure or deterioration of the sensor voltage,
resistance, impedance, current, response rate, amplitude, offset, or
other characteristic(s) that would cause an engine's emissions to
exceed the emissions thresholds for NOX sensors as shown in
Table 1 of this paragraph (g).
    (B) Circuit integrity. The OBD system must detect malfunctions of
the sensor related to a lack of circuit continuity or signal out-of-
range values.
     (C) Feedback function.The OBD system must detect a malfunction of
the sensor if the emission control system (e.g., EGR, SCR, or
NOX adsorber) is unable to use that sensor as a feedback
input (e.g., causes limp-home or open-loop operation).
    (D) Monitoring function. To the extent feasible, the OBD system
must detect a malfunction of the sensor when the sensor output voltage,
resistance, impedance, current, amplitude, activity, offset, or other
characteristics are no longer sufficient for use as an OBD system
monitoring device (e.g., for catalyst, EGR, SCR, or NOX
adsorber monitoring).
    (v) Malfunction criteria for other exhaust gas sensors. For other
exhaust gas sensors, the manufacturer must submit a monitoring plan to
the Administrator for approval. The plan must include data and/or
engineering evaluations that demonstrate that the monitoring plan is as
reliable and effective as the monitoring required in paragraphs
(g)(9)(ii) through (g)(9)(iv) of this section.
    (vi) Malfunction criteria for exhaust gas sensor heaters.
    (A) The OBD system must detect a malfunction of the heater
performance when the current or voltage drop in the heater circuit is
no longer within the manufacturer's specified limits for normal
operation (i.e., within the criteria required to be met by the
component vendor for heater circuit performance at high mileage). The
manufacturer may use other malfunction criteria for heater performance
malfunctions. To do so, the manufacturer must be able to demonstrate
via data and/or an engineering evaluation that the monitor is reliable
and robust.
    (B) The OBD system must detect malfunctions of the heater circuit
including open or short circuits that conflict with the commanded state
of the heater (e.g., shorted to 12 Volts when commanded to 0 Volts
(ground)).
    (vii) Monitoring conditions for exhaust gas sensors.
    (A) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraphs (g)(9)(ii)(A), (g)(9)(iii)(A),
and (g)(9)(iv)(A) of this section (i.e., sensor performance) in
accordance with paragraphs (c) and (d) of this section. For purposes of
tracking and reporting as required in paragraph (d)(1) of this section,
all monitors used to detect malfunctions identified in paragraphs
(g)(9)(ii)(A), (g)(9)(iii)(A), and (g)(9)(iv)(A) of this section must
be tracked separately but reported as a single set of values as
specified in paragraph (e)(1)(iii) of this section.
    (B) The manufacturer must define the monitoring conditions for
malfunctions identified in paragraphs (g)(9)(ii)(D), (g)(9)(iii)(D),
and (g)(9)(iv)(D) of this section (i.e., monitoring function) in
accordance with paragraphs (c) and (d) of this section with the
exception that monitoring must occur every time the monitoring
conditions are met during the drive cycle rather than once per drive
cycle as required in paragraph (c)(2) of this section.
    (C) Except as provided for in paragraph (g)(9)(vii)(D) of this
paragraph (g)(9), the OBD system must monitor continuously for
malfunctions identified in paragraphs (g)(9)(ii)(B), (g)(9)(ii)(C),
(g)(9)(iii)(B), (g)(9)(iii)(C), (g)(9)(iv)(B), and (g)(9)(iv)(C) (i.e.,
circuit integrity and feedback function).
    (D) A manufacturer may request approval to disable continuous
exhaust gas sensor monitoring when an exhaust gas sensor malfunction
cannot be distinguished from other effects (e.g., disable monitoring
for out-of-range on the low side during fuel cut conditions). To do so,
the manufacturer must demonstrate via data and/or engineering analyses
that a properly functioning sensor cannot be distinguished from a
malfunctioning sensor and that the disablement interval is limited only
to that necessary for avoiding false malfunction detection.
    (viii) Monitoring conditions for exhaust gas sensor heaters.
    (A) The manufacturer must define monitoring conditions for
malfunctions identified in paragraph (g)(9)(vi)(A) of this section
(i.e., sensor heater performance) in accordance with paragraphs (c) and
(d) of this section.
    (B) The OBD system must monitor continuously for malfunctions
identified in paragraph (g)(9)(vi)(B) of this section (i.e., circuit
malfunctions).
    (ix) Exhaust gas sensor and sensor heater MIL activation and DTC
storage. The MIL must activate and DTCs must be stored according to the
provisions of paragraph (b) of this section.
    (10) Variable Valve Timing (VVT) system monitoring.
    (i) General. The OBD system must monitor the VVT system on engines
so equipped for target error and slow response malfunctions. The
individual electronic components (e.g., actuators, valves, sensors)
that are used in the VVT system must be monitored in accordance with
the comprehensive components requirements in paragraph (i)(3) of this
section.
    (ii) VVT system malfunction criteria.
    (A) VVT system target error. The OBD system must detect a
malfunction prior to any failure or deterioration in the capability of
the VVT system to achieve the commanded valve timing and/or control
within a crank angle and/or lift tolerance that would cause an engine's

emissions to exceed the emission thresholds for ``other monitors'' as
shown in Table 1 of this paragraph (g).
    (B) VVT slow response. The OBD system must detect a malfunction
prior to any failure or deterioration in the capability of the VVT
system to achieve the commanded valve timing and/or control within a
manufacturer-specified time that would cause an engine's emissions to
exceed the emission thresholds for ``other monitors'' as shown in Table
1 of this paragraph (g).
    (C) For engines in which no failure or deterioration of the VVT
system could result in an engine's emissions exceeding the applicable
emissions thresholds of paragraphs (g)(10)(ii)(A) and (g)(10)(ii)(B) of
this section, the OBD system must detect a malfunction of the VVT
system when proper functional response of the system to computer
commands does not occur.
    (iii) VVT system monitoring conditions. Manufacturers must define
the monitoring conditions for VVT system malfunctions identified in
paragraph (g)(10)(ii) of this section in accordance with paragraphs (c)
and (d) of this section, with the exception that monitoring must occur
every time the monitoring conditions are met during the drive cycle
rather than once per drive cycle as required in paragraph (c)(2) of
this section. For purposes of tracking and reporting as required in
paragraph (d)(1) of this section, all monitors used to detect
malfunctions identified in paragraph (g)(10)(ii) of this section must
be tracked separately but reported as a single set of values as
specified in paragraph (e)(1)(iii) of this section.
    (iv) VVT MIL activation and DTC storage. The MIL must activate and
DTCs must be stored according to the provisions of paragraph (b) of
this section.
    (h) OBD monitoring requirements for gasoline-fueled/spark-ignition
engines. The following table shows the thresholds at which point
certain components or systems, as specified in this paragraph (h), are
considered malfunctioning.

      Table 2.--OBD Emissions Thresholds for Gasoline-Fueled/Spark-Ignition Engines Meant for Placement in
                             Applications Greater Than 14,000 Pounds GVWR (g/bhp-hr)
----------------------------------------------------------------------------------------------------------------
                                                                                Sec.   86.010-18
            Component                    NOX                 NMHC                 CO              reference
----------------------------------------------------------------------------------------------------------------
Catalyst system.................  1.75x std........  1.75x std..........  .................  (h)(6).
Evaporative emissions control     .................  0.150 inch leak....  .................  (h)(7).
 system.
``Other monitors'' with           1.5x std.........  1.5x std...........  1.5x std.........  (h)(1), (h)(2),
 emissions thresholds.                                                                        (h)(3), (h)(4),
                                                                                (h)(5), (h)(8),
                                                                                (h)(9).
----------------------------------------------------------------------------------------------------------------
Notes: 1.75x std means a multiple of 1.75 times the applicable emissions standard; these emissions thresholds
  apply to the monitoring requirements of paragraph (h) of this section 86.010-18; The evaporative emissions
  control system threshold is not, technically, an emissions threshold but rather a leak size that must be
  detected; nonetheless, for ease we refer to this as the threshold.

    (1) Fuel system monitoring.
    (i) General. The OBD system must monitor the fuel delivery system
to determine its ability to provide compliance with emission standards.
    (ii) Fuel system malfunction criteria.
    (A) The OBD system must detect a malfunction of the fuel delivery
system (including feedback control based on a secondary oxygen sensor)
when the fuel delivery system is unable to maintain an engine's
emissions at or below the emissions thresholds for ``other monitors''
as shown in Table 2 of this paragraph (h).
    (B) Except as provided for in paragraph (h)(1)(ii)(C) of this
section, if the engine is equipped with adaptive feedback control, the
OBD system must detect a malfunction when the adaptive feedback control
has used up all of the adjustment allowed by the manufacturer.
    (C) If the engine is equipped with feedback control that is based
on a secondary oxygen (or equivalent) sensor, the OBD system is not
required to detect a malfunction of the fuel system solely when the
feedback control based on a secondary oxygen sensor has used up all of
the adjustment allowed by the manufacturer. However, if a failure or
deterioration results in engine emissions that exceed the emissions
thresholds for ``other monitors'' as shown in Table 2 of this paragraph
(h), the OBD system is required to detect a malfunction.
    (D) The OBD system must detect a malfunction whenever the fuel
control system fails to enter closed loop operation following engine
start within a manufacturer specified time interval. The specified time
interval must be supported by data and/or engineering analyses
submitted by the manufacturer.
    (E) The manufacturer may adjust the malfunction criteria and/or
monitoring conditions to compensate for changes in altitude, for
temporary introduction of large amounts of purge vapor, or for other
similar identifiable operating conditions when such conditions occur.
    (iii) Fuel system monitoring conditions. The fuel system must be
monitored continuously for the presence of a malfunction.
    (iv) Fuel system MIL activation and DTC storage.
    (A) A pending DTC must be stored immediately upon the fuel system
exceeding the malfunction criteria established in paragraph (h)(1)(ii)
of this section.
    (B) Except as provided for in paragraph (h)(1)(iv)(C) of this
section, if a pending DTC is stored, the OBD system must activate the
MIL immediately and store a MIL-on DTC if a malfunction is again
detected during either the drive cycle immediately following storage of
the pending DTC regardless of the conditions encountered during that
drive cycle, or on the next drive cycle in which similar conditions are
encountered to those that occurred when the pending DTC was stored.
Similar conditions means engine conditions having an engine speed
within 375 rpm, load conditions within 20 percent, and the same warm up
status (i.e., cold or hot) as the engine conditions stored pursuant to
paragraph (h)(1)(iv)(E) of this section. Other definitions of similar
conditions may be used but must result in comparable timeliness and
reliability in detecting similar engine operation.
    (C) The pending DTC may be erased at the end of the next drive
cycle in which similar conditions have been encountered without having
again exceeded the specified fuel system malfunction criteria. The
pending DTC may also be erased if similar conditions are not
encountered during the 80 drive cycles immediately following detection
of the potential malfunction for which the pending DTC was stored.
    (D) Storage of freeze frame conditions. The OBD system must store
and erase freeze frame conditions either in conjunction with storing
and erasing a pending DTC or in conjunction with storing and erasing a
MIL-on DTC. Freeze frame information associated with a fuel system
malfunction shall be

stored in preference to freeze frame information required elsewhere in
paragraphs (h) or (i) of this section.
    (E) Storage of fuel system conditions for determining similar
conditions of operation. The OBD must store the engine speed, load, and
warm-up status present at the time it first detects a potential
malfunction meeting the criteria of paragraph (h)(1)(ii) of this
section and stores a pending DTC.
    (F) Deactivating the MIL. The MIL may be extinguished after three
sequential driving cycles in which similar conditions have been
encountered without detecting a malfunction of the fuel system.
    (2) Engine misfire monitoring.
    (i) General.
    (A) The OBD system must monitor the engine for misfire causing
catalyst damage and misfire causing excess emissions.
    (B) The OBD system must identify the specific cylinder that is
misfiring. The manufacturer may store a general misfire DTC instead of
a cylinder specific DTC under certain operating conditions. To do so,
the manufacturer must submit data and/or engineering analyses that
demonstrate that the misfiring cylinder cannot be identified reliably
when the conditions occur.
    (C) If more than one cylinder is misfiring, a separate DTC must be
stored to indicate that multiple cylinders are misfiring unless
otherwise allowed by this paragraph (h)(2). When identifying multiple
cylinder misfire, the OBD system is not required to also identify using
separate DTCs each of the misfiring cylinders individually. If more
than 90 percent of the detected misfires occur in a single cylinder, an
appropriate DTC may be stored that indicates the specific misfiring
cylinder rather than storing the multiple cylinder misfire DTC. If two
or more cylinders individually have more than 10 percent of the total
number of detected misfires, a multiple cylinder DTC must be stored.
    (ii) Engine misfire malfunction criteria.
    (A) Misfire causing catalyst damage. The manufacturer must
determine the percentage of misfire evaluated in 200 revolution
increments for each engine speed and load condition that would result
in a temperature that causes catalyst damage. If this percentage of
misfire is exceeded, it shall be considered a malfunction that must be
detected. For every engine speed and load condition for which this
percentage of misfire is determined to be lower than five percent, the
manufacturer may set the malfunction criteria at five percent. The
manufacturer may use a longer interval than 200 revolutions but only
for determining, on a given drive cycle, the first misfire exceedance
as provided in paragraph (h)(2)(iv)(A) of this section. To do so, the
manufacturer must demonstrate that the interval is not so long that
catalyst damage would occur prior to the interval being elapsed.
    (B) Misfire causing emissions to exceed the applicable thresholds.
The manufacturer must determine the percentage of misfire evaluated in
1000 revolution increments that would cause emissions from an emissions
durability demonstration engine to exceed the emissions thresholds for
``other monitors'' as shown in Table 2 of this paragraph (h) if that
percentage of misfire were present from the beginning of the test. If
this percentage of misfire is exceeded, regardless of the pattern of
misfire events (e.g., random, equally spaced, continuous), it shall be
considered a malfunction that must be detected. To establish this
percentage of misfire, the manufacturer must use misfire events
occurring at equally spaced, complete engine cycle intervals, across
randomly selected cylinders throughout each 1000-revolution increment.
If this percentage of misfire is determined to be lower than one
percent, the manufacturer may set the malfunction criteria at one
percent. The manufacturer may use a longer interval than 1000
revolutions. To do so, the manufacturer must demonstrate that the
strategy would be equally effective and timely at detecting misfire.
    (iii) Engine misfire monitoring conditions.
    (A) The OBD system must monitor continuously for misfire under the
following conditions: from no later than the end of the second
crankshaft revolution after engine start; during the rise time and
settling time for engine speed to reach the desired idle engine speed
at engine start-up (i.e., ``flare-up'' and ``flare-down''); and, under
all positive torque engine speeds and load conditions except within the
engine operating region bound by the positive torque line (i.e., engine
load with the transmission in neutral), and the points represented by
an engine speed of 3000 rpm with the engine load at the positive torque
line and the redline engine speed with the engine's manifold vacuum at
four inches of mercury lower than that at the positive torque line. For
this purpose, redline engine speed is defined as either the recommended
maximum engine speed as displayed on the instrument panel tachometer,
or the engine speed at which fuel shutoff occurs.
    (B) If an OBD monitor cannot detect all misfire patterns under all
required engine speed and load conditions as required by paragraph
(h)(2)(iii)(A) of this section, the OBD system may still be acceptable.
The Administrator will evaluate the following factors in making a
determination: the magnitude of the region(s) in which misfire
detection is limited; the degree to which misfire detection is limited
in the region(s) (i.e., the probability of detection of misfire
events); the frequency with which said region(s) are expected to be
encountered in-use; the type of misfire patterns for which misfire
detection is troublesome; and demonstration that the monitoring
technology employed is not inherently incapable of detecting misfire
under the required conditions (i.e., compliance can be achieved on
other engines). The evaluation will be based on the following misfire
patterns: equally spaced misfire occurring on randomly selected
cylinders; single cylinder continuous misfire; and paired cylinder
(cylinders firing at the same crank angle) continuous misfire.
    (C) The manufacturer may use monitoring system that has reduced
misfire detection capability during the portion of the first 1000
revolutions after engine start that a cold start emission reduction
strategy is active that reduces engine torque (e.g., spark retard
strategies). To do so, the manufacturer must demonstrate that the
probability of detection is greater than or equal to 75 percent during
the worst case condition (i.e., lowest generated torque) for a vehicle
operated continuously at idle (park/neutral idle) on a cold start
between 50 and 86 degrees Fahrenheit and that the technology cannot
reliably detect a higher percentage of the misfire events during the
conditions.
    (D) The manufacturer may disable misfire monitoring or use an
alternative malfunction criterion when misfire cannot be distinguished
from other effects. To do so, the manufacturer must demonstrate that
the disablement interval or the period of use of an alternative
malfunction criterion is limited only to that necessary for avoiding
false detection and for one or more of the following operating
conditions: rough road; fuel cut; gear changes for manual transmission
vehicles; traction control or other vehicle stability control
activation such as anti-lock braking or other engine torque
modifications to enhance vehicle stability; off-board control or
intrusive activation of vehicle components or monitors during service
or assembly plant testing; portions of intrusive evaporative system or
EGR monitors that can significantly affect engine stability (i.e.,
while the purge valve is open during the vacuum pull-down of a

evaporative system leak check but not while the purge valve is closed
and the evaporative system is sealed or while an EGR monitor causes the
EGR valve to be cycled intrusively on and off during positive torque
conditions); or, engine speed, load, or torque transients due to
throttle movements more rapid than those that occur over the FTP cycle
for the worst case engine within each engine family. In general, the
Administrator will not approve disablement for conditions involving
normal air conditioning compressor cycling from on-to-off or off-to-on,
automatic transmission gear shifts (except for shifts occurring during
wide open throttle operation), transitions from idle to off-idle,
normal engine speed or load changes that occur during the engine speed
rise time and settling time (i.e., ``flare-up'' and ``flare-down'')
immediately after engine starting without any vehicle operator-induced
actions (e.g., throttle stabs), or excess acceleration (except for
acceleration rates that exceed the maximum acceleration rate obtainable
at wide open throttle while the vehicle is in gear due to abnormal
conditions such as slipping of a clutch).
    (iv) MIL activation and DTC storage for engine misfire causing
catalyst damage.
    (A) Pending DTCs. A pending DTC must be stored immediately if,
during a single drive cycle, the specified misfire percentage described
in paragraph (h)(2)(ii)(A) of this section is exceeded three times when
operating in the positive torque region encountered during a FTP cycle
or is exceeded on a single occasion when operating at any other engine
speed and load condition in the positive torque region defined in
paragraph (h)(2)(iii)(A) of this section. Immediately after a pending
DTC is stored pursuant to this paragraph, the MIL must blink once per
second at all times during the drive cycle that engine misfire is
occurring. The MIL may be deactivated during those times that misfire
is not occurring. If, at the time that a catalyst damaging misfire
malfunction occurs, the MIL is already activated for a malfunction
other than misfire, the MIL must still blink once per second at all
times during the drive cycle that engine misfire is occurring. If
misfire ceases, the MIL must stop blinking but remain activated as
appropriate in accordance with the other malfunction.
    (B) MIL-on DTCs. If a pending DTC is stored in accordance with
paragraph (h)(2)(iv)(A) of this section, the OBD system must
immediately store a MIL-on DTC if the percentage of misfire described
in paragraph (h)(2)(ii)(A) of this section is again exceeded one or
more times during either the drive cycle immediately following storage
of the pending DTC, regardless of the conditions encountered during
that drive cycle, or on the next drive cycle in which similar
conditions are encountered to those that occurred when the pending DTC
was stored. If, during a previous drive cycle, a pending DTC is stored
in accordance with paragraph (h)(2)(iv)(A) of this section, a MIL-on
DTC must be stored immediately upon exceeding the percentage misfire
described in paragraph (h)(2)(ii)(A) of this section regardless of the
conditions encountered. Upon storage of a MIL-on DTC, the MIL must
blink once per second at all times during the drive cycle that engine
misfire is occurring. If misfire ceases, the MIL must stop blinking but
remain activated until the conditions are met for extinguishing the
MIL.
    (C) Erasure of pending DTCs. Pending DTCs stored in accordance with
paragraph (h)(2)(iv)(A) of this section must be erased at the end of
the next drive cycle in which similar conditions are encountered to
those that occurred when the pending DTC was stored provided no
exceedances have been detected of the misfire percentage described in
paragraph (h)(2)(ii)(A) of this section. The pending DTC may also be
erased if similar conditions are not encountered during the next 80
drive cycles immediately following storage of the pending DTC.
    (D) Exemptions for engines with fuel shutoff and default fuel
control. In engines that provide for fuel shutoff and default fuel
control to prevent over fueling during catalyst damaging misfire
conditions, the MIL need not blink as required by paragraphs
(h)(2)(iv)(A) and (h)(2)(iv)(B) of this section. Instead, the MIL may
be activated continuously upon misfire detection provided that the fuel
shutoff and default fuel control are activated immediately upon misfire
detection. Fuel shutoff and default fuel control may be deactivated
only when the engine is outside of the misfire range except that the
manufacturer may periodically, but not more than once every 30 seconds,
deactivate fuel shutoff and default fuel control to determine if the
catalyst damaging misfire is still occurring. Normal fueling and fuel
control may be resumed if the catalyst damaging misfire is no longer
occurring.
    (E) The manufacturer may use a strategy that activates the MIL
continuously rather than blinking the MIL during extreme catalyst
damage misfire conditions (i.e., catalyst damage misfire occurring at
all engine speeds and loads). Use of such a strategy must be limited to
catalyst damage misfire levels that cannot be avoided during reasonable
driving conditions. To use such a strategy, the manufacturer must be
able to demonstrate that the strategy will encourage operation of the
vehicle in conditions that will minimize catalyst damage (e.g., at low
engine speeds and loads).
    (v) MIL activation and DTC storage for engine misfire causing
emissions to exceed applicable emissions thresholds.
    (A) Immediately upon detection, during the first 1000 revolutions
after engine start of the misfire percentage described in paragraph
(h)(2)(ii)(B) of this section, a pending DTC must be stored. If such a
pending DTC is stored already and another such exceedance of the
misfire percentage is detected within the first 1000 revolutions after
engine start on any subsequent drive cycle, the MIL must activate and a
MIL-on DTC must be stored. The pending DTC may be erased if, at the end
of the next drive cycle in which similar conditions are encountered to
those that occurred when the pending DTC was stored, there has been no