particulate filter elements meets the four criteria of 40 CFR
1036.125(g). We estimate that EGR valves, EGR coolers, and RESS also
meet the 40 CFR 1036.125(g) criteria and, under this proposal,
manufacturers would only be able to schedule replacement of these three
components if the manufacturer pays for it. In the HD Omnibus
rulemaking, CARB included turbochargers in their list of components
``not replaceable'' during the regulatory useful life. Under the
proposed criteria specified in 40 CFR 1036.125(g), scheduled
turbocharger maintenance would not meet all four criteria of the 40 CFR
1036.125(g), since a turbocharger's primary function is not to reduce
emissions and an underperforming or failed turbocharger would degrade
engine performance. We request comment on including turbochargers as
components that should have limited replacement irrespective of the
four 40 CFR 1036.125(g) criteria. We also request comment on other
components that meet the criteria, or other criteria EPA should
consider when determining which components should have limited
replacement during the scheduled maintenance approval process.
vii. Source of Parts and Repairs
    CAA section 207(c)(3) prohibits manufacturers from requiring
maintenance work be completed only by OEM-authorized dealers. We are
proposing a new paragraph 40 CFR 1036.125(f) to clarify that
manufacturers cannot limit the source of parts and repairs for
maintenance.\562\ This paragraph would require manufacturers to clearly
state in their maintenance instructions that owners can choose any
repair shop or person to perform maintenance. Furthermore, the
manufacturers cannot specify a particular brand, trade, or corporate
name for components or service and cannot deny a warranty claim due to
``improper maintenance'' based on owners choosing not to use a
franchised dealer or service facility or a specific brand of part. The
existing and proposed provisions allow manufacturers to specify a
particular service facility and brand of parts only if they are
providing the service or component to the owner without charge or if
the manufacturer convinces EPA during the approval process that the
engine will only work properly with the identified service or
component.
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    \562\ This provision has been adopted in the standard-setting
parts of several other sectors, including heavy-duty vehicles (see
1037.125(f)).
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viii. Maintenance Instructions
    Our proposed 40 CFR 1036.125 preserves the requirement that the
manufacturer provide written instructions for properly maintaining and
using the engine and emission control system. We are proposing a new 40
CFR 1036.125(h) to describe the information that would be required in
an owner's manual. The proposed 40 CFR 1036.125(h) generally migrates
the existing maintenance instruction provisions specified in 40 CFR
86.010-38(a) through (i) with updates as described in Sections IV.B.3
and IV.C of this preamble. As noted in Section IV.B.3, our
serviceability proposal supplements the current service information
provisions currently specified in 40 CFR 86.010-38(j). We are not
proposing to migrate the service information provisions into part 1036;
rather, we would preserve their current location in 40 CFR 86.010-
38(j), with updated references to any sections migrated to the new part
1036.
    While 40 CFR 1036.120(d) allows manufacturers to deny warranty
claims for improper maintenance and use, owners have expressed concern
that it is unclear what recordkeeping is needed to document proper
maintenance and use. Consistent with the current 40 CFR 86.010-
38(a)(2), we propose that manufacturers describe in the owner's manual
the documentation they consider appropriate to demonstrate the engine
and emission control system are properly maintained (see 40 CFR
1036.125(h)(2)). Manufacturers should be able to identify specific
examples of maintenance practices they would consider improper, and to
identify their expectations for documenting routine maintenance and
repairs related to warranty claims. If a manufacturer requires a
maintenance log as part of their process for reviewing warranty claims,
we expect the owner's manual would provide an example log that includes
the required maintenance tasks and intervals and clearly states that
warranty claims require an up-to-date maintenance record. We would be
able to review the manufacturers information describing the parameters
and documentation for demonstrating proper maintenance before granting
certification for an engine family.
ix. Performing Scheduled Maintenance on Test Engines
    Current provisions defining the limits on maintenance that can be
performed during testing are specified in 40 CFR 86.004-25(e) and (f).
We are not migrating those provisions into part 1036; instead, we are
proposing that the general provisions currently in 40 CFR 1065, subpart
E, would apply for criteria pollutant standards for model year 2027 and
later engines.\563\
---------------------------------------------------------------------------

    \563\ We believe the idle speed adjustments, currently 40 CFR
86.004-25(e)(1), are obsolete, since idle is usually set by the ECM
and it would not need to be adjusted prior to testing.
---------------------------------------------------------------------------

    We are proposing to update 40 CFR 1065.410(c) to clarify that
inspections performed during testing include electronic monitoring of
engine parameters, such as prognostic systems. Manufacturers that
include prognostic

systems as part of their engine packages to identify or predict
malfunctioning components may use those systems during durability
testing and would include any maintenance performed as a result of
those systems, consistent with 40 CFR 1065.410(d), in their application
for certification. We note that, in order to apply these electronic
monitoring systems in testing, the inspection tool (e.g., prognostic
system) must be available to all customers or accessible at dealerships
and other service outlets.

C. Onboard Diagnostics

    As used here, the terms ``onboard diagnostics'' and ``OBD'' refer
to systems of electronic controllers and sensors required by regulation
to detect malfunctions of engines and emission controls. EPA's existing
OBD regulations for heavy-duty engines are contained in 40 CFR 86.010-
18, which were initially promulgated February 24, 2009 (74 FR 8310).
EPA's OBD requirements promulgated in 2009 were harmonized with CARB's
OBD program then in place. Since 2009, CARB has revised their OBD
requirements, while EPA's requirements have not changed. EPA's existing
OBD program allows manufacturers to demonstrate how the OBD system they
have designed to comply with California OBD requirements for engines
used in applications greater than 14,000 pounds also complies with the
intent of existing EPA OBD requirements.\564\ When applying for EPA 50-
state certification, all manufacturers currently seek OBD approval from
CARB for OBD systems in engine families and then demonstrate compliance
with EPA's OBD regulations through this provision. Currently all heavy-
duty manufacturers are certifying to the revised CARB OBD regulations
that took effect in 2019.\565\
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    \564\ See 40 CFR 86.010-18(a)(5).
    \565\ CARB Final Rulemaking Package took effect on October 3,
2019, available here: https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
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    As part of our effort to evaluate EPA compliance programs, we are
proposing to update our OBD regulations both to better address newer
diagnostic methods and available technologies and to streamline
provisions where possible. These revised regulations are being proposed
in 40 CFR 1036.110.
1. Incorporation of California OBD Regulations by Reference
    CARB OBD regulations for heavy-duty engines are codified in title
13, California Code of Regulations, sections 1968.2, 1968.5, 1971.1 and
1971.5. These regulations have been updated by CARB several times since
EPA initially promulgated HD OBD regulations in 2009. The most recent
updates were in October of 2019 and start to phase in with MY
2022.\566\ It is possible that CARB could further update their heavy-
duty OBD regulations prior to the final rulemaking for this program. In
July 2021, CARB proposed changes to their OBD program.\567\ These
amendments may include adding the use of Unified Diagnostic Services
(``UDS'') to address the concern about the limited number of remaining,
undefined 2-byte diagnostic trouble codes and the need for additional
codes for hybrid vehicles. These amendments may also modify freeze
frame requirements, in-use monitoring performance ratio requirements,
and expand readiness group lists. As discussed below, our proposal
intends to harmonize with the majority of CARB's existing OBD
regulations, as appropriate and consistent with the CAA. EPA also seeks
comment on harmonizing with any future OBD amendments that may result
from this proposal.
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    \566\ The most recent updates for 13 CCR 1971.1 and 13 CCR
1971.5 are available here https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
    \567\ CARB 2021 OBD II and Heavy-Duty OBD (HD OBD) Regulatory
Documents Public Notice for OBD Regulations Update, July 22, 2021.
Available here: https://ww2.arb.ca.gov/resources/documents/obd-ii-regulations-and-rulemaking.
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    In response to the ANPR, EPA received a number of comments
supportive of EPA's adoption of the revised CARB OBD program including
the 2019 rule amendments.\568\ In particular, many commenters were
supportive of the new tracking requirements contained in CARB's updated
OBD program, known as the Real Emissions Assessment Logging (``REAL'')
program to track real-world emissions systems performance of heavy-duty
engines. This update requires the collection of onboard data using
existing OBD sensors and other vehicle performance parameters, which
would allow the assessment of real-world, in-use emission performance
relative to laboratory performance beginning in the 2022 model year.
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    \568\ For example, see comments from Roush, Docket ID EPA-HQ-
OAR-2019-0555-0303; International Council on Climate Change, Docket
ID EPA-HQ-OAR-2019-0555-0304; and the Metropolitan Washington
Council of Governments, Docket ID EPA-HQ-OAR-2019-0555-0286.
---------------------------------------------------------------------------

    In developing the ANPR, we considered proposing to update the
current text in 40 CFR 86.010-18 and migrate it into the new 40 CFR
1036.110. However, given industry's familiarity with the current CARB
regulations, we have decided instead to propose incorporating by
reference in 40 CFR 1036.110 the existing CARB OBD regulations updated
in 2019 as the starting point for our updated OBD regulations. EPA's
proposed OBD requirements are closely aligned with CARB's existing
requirements with a few exceptions. We are proposing to exclude certain
provisions that are not appropriate for a federal program and to
include additional elements to improve on the usefulness of OBD systems
for users.\569\ We are taking comment on whether and to what extent we
should harmonize with CARB's next expected update to their OBD
regulations, or whether the proposed language in 40 CFR 1036.110(b) is
sufficient to accommodate any future divergence in CARB and EPA OBD
requirements. EPA anticipates that this language would allow for EPA
approval of OBD systems that meet certain parts of updated CARB
requirements (e.g., updated communication protocols), as long as such
provisions meet the intent of EPA OBD requirements.
---------------------------------------------------------------------------

    \569\ The legal effect of incorporation by reference is that the
material is treated as if it were published in the Federal Register
and CFR. This material, like any other properly issued rule, has the
force and effect of law. Congress authorized incorporation by
reference in the Freedom of Information Act to reduce the volume of
material published in the Federal Register and CFR. (See 5 U.S.C.
552(a) and 1 CFR part 51). See https://www.archives.gov/federal-register/cfr/ibr-locations.html for additional information.
---------------------------------------------------------------------------

i. OBD Threshold Requirements
    The most essential component of the OBD program is the threshold
requirement. Heavy-duty engine emission control components can
contribute to an increase in emissions if they malfunction and
therefore, they must be monitored by OBD systems. Existing OBD
requirements specify how OBD systems must monitor certain components
and indicate a fault code prior to when emissions would exceed emission
standards by a certain amount, known as an emission threshold. Emission
thresholds for these components are generally either an additive value
above the exhaust emission standard, or a multiple of the standard.
Reductions to emission standards mean that without additional action,
OBD thresholds would also be reduced proportionally.
    The CARB Omnibus Amendments to the HD OBD regulation include a
provision that will not proportionally reduce NOX and PM OBD
threshold requirements that correspond to the new lower emission
standards.\570\ This

means the future numerical values of OBD NOX and PM
thresholds would remain unchanged from today's numerical thresholds as
a part of that rulemaking. CARB noted in the Omnibus rule that more
time is needed to fully evaluate the capability of HD OBD monitors to
accommodate lower thresholds that would correspond to lower emission
levels. EPA is proposing to harmonize with this policy and not lower
OBD NOX and PM threshold levels in our proposed OBD
regulations at this time. EPA may consider updating threshold
requirements in a separate action which may align with a future CARB
action. Specifically, we are proposing that heavy-duty compression-
ignition engines would be subject to NOX and PM thresholds
of 0.4 g/hp-hr and 0.03 g/hp-hr, respectively, for operation on the FTP
and SET duty cycles. For spark ignition engines, we are proposing the
following thresholds to align with CARB: 0.30 g/hp-hr for monitors
detecting a malfunction before NOX emissions exceed 1.5
times the applicable standard, 0.35 g/hp-hr for monitors detecting a
malfunction before NOX emissions exceed 1.75 times the
applicable standard, and 0.60 g/hp-hr for monitors detecting a
malfunction before NOX emissions exceed 3.0 times the
applicable standard. For spark ignition engines, we are also proposing
a 0.015 g/hp-hr threshold for PM emissions to align with CARB. EPA is
seeking comment on this proposed action, or whether thresholds should
be modified as a part of this proposal.\571\
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    \570\ California Air Resources Board. Heavy-Duty Omnibus
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \571\ California Air Resources Board. Staff Report: Initial
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated
Amendments. June 23, 2020. https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf.
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ii. CARB OBD Provisions Revised or Not Included in the Proposed Federal
Program
    EPA is proposing to adopt the majority of the CARB OBD program.
However, we are proposing that some provisions may not be appropriate
for the federal regulations.\572\ As part of CARB's development of the
2019 OBD program, a number of stakeholders submitted comments to
CARB.\573\ In developing this proposal, we have reviewed the concerns
raised by stakeholders to CARB to help us determine what provisions may
not be appropriate in a federal program. In a new 40 CFR 1036.110(b),
we are proposing clarifications and changes to the 2019 CARB
regulations we are otherwise incorporating by reference, including
provisions related to:
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    \572\ Note that we are making no determination in this proposal
about the appropriateness of these provisions for CARB regulation.
    \573\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055.
``Comments submitted to the California Air Resources Board during
the development of updated heavy-duty OBD requirements.'' October 1,
2021.
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    1. Providing flexibilities to delay compliance up to three model
years for small manufacturers who have not previously certified an
engine in California,
    2. Allowing good engineering judgment to correlate the CARB OBD
standards with EPA OBD standards,
    3. Clarifying that engines must comply with OBD requirements
throughout EPA's useful life as specified in 40 CFR 1036.104, which may
differ from CARB for some model years,
    4. Clarifying that the purpose and applicability statements in 13
CCR 1971.1(a) and (b) do not apply,
    5. Specifying NOX and PM threshold requirements,
    6. Not requiring the manufacturer self-testing and reporting
requirements in 13 CCR 1971.1(i)(2.3) and 1971.1(i)(2.4),
    7. Retaining and migrating our existing deficiency policy into
proposed 40 CFR 1036.110(d), and specifying that the deficiency
provisions in 13 CCR 1971.1(k) do not apply,
    8. Requiring additional freeze frame data requirements,
    9. Requiring additional data stream parameters for compression- and
spark-ignition engines, and
    10. Providing flexibilities to reduce redundant demonstration
testing requirements for engines certified to CARB OBD requirements.
    Manufacturers indicated concern with the existing manufacturer
self-testing (``MST'') requirements in 13 CCR 1971.1(i)(2.3 and 2.4).
This provision requires manufacturers to obtain vehicles that have
reached their full useful life and remove the engine for extensive
testing to quantify emission performance and deterioration of the
system elements in a manner that allows comparison to deterioration and
performance levels achieved with the manufacturer's accelerated aging
process. In 2009, when EPA initially promulgated OBD regulations for
the heavy-duty industry, we were concerned about the difficulty and
expense of removing an in-use engine from a vehicle for engine
dynamometer testing, and we did not adopt such a requirement at that
time.\574\ EPA continues to be concerned that the cost of this testing
may be significant and is not warranted for the federal program.
Further, we believe that the information CARB gains from this program
can be shared with EPA and would help inform us of the ongoing progress
manufacturers are making with OBD compliance. Therefore, while we are
proposing to exclude this CARB OBD provision from the EPA OBD
regulations at this time, we are proposing that manufacturers submit
the results of any MST testing performed for CARB to EPA.
---------------------------------------------------------------------------

    \574\ 74 FR 8347, February 24, 2009.
---------------------------------------------------------------------------

    EPA requests comments and information on whether there are
opportunities for further reducing OBD compliance and certification
costs of the federal program through increasing the use of modeling or
other calculation-based methods as a part of the certification process
which could potentially replace certain testing requirements. Examples
could include test-out provisions or testing required for infrequent
adjustment factors. CARB's OBD program includes provisions that may
allow for certain components to meet specific test-out criteria which
would exempt them from monitoring requirements. For example, 13 CCR
1971.1(e)(3.2.6)(B) describes how EGR catalysts would be exempt from
monitoring if manufacturers can show that both of the following
criteria are satisfied: (1) No malfunction of the EGR catalyst can
cause emissions to increase by 15 percent or more of the applicable
NMHC, NOX, CO, or PM standard as measured from an applicable
emission test cycle; and (2) no malfunction of the EGR catalyst can
cause emissions to exceed the applicable NMHC, NOX, CO, or
PM standard as measured from an applicable emission test cycle. EPA is
seeking comment on whether manufacturers could use modeling or other
calculation-based methods to determine if such test-out criteria are
met.
    Another example where the use of modeling or other calculation-
based methods could reduce testing requirements is for the calculation
of infrequent regeneration adjustment factors for engines equipped with
emission controls that experience infrequent regeneration events. These
adjustment factors are used to account for emissions from regeneration
events when determining compliance with EPA standards. Manufacturers
must conduct testing to develop these adjustment factors using the same
deteriorated component(s) used to determine if the test-out criteria
are being met. EPA is seeking comment on whether it is possible and
appropriate to consider modeling- or calculation-based methods to
replace certain hardware-based test methods in these or other

areas of certification to reduce costs without reducing the
functionality of the existing OBD requirements.
    EPA is seeking comment on how these or other provisions in the
existing or any potential upcoming CARB OBD regulation could be
modified to better suit the federal OBD program.\575\ It is important
to emphasize that by not incorporating certain existing CARB OBD
requirements (e.g., the in-use engine test program) into our
regulations, we are not waiving our authority to require such testing
on a case-by-case basis. CAA section 208 gives EPA broad authority to
require manufacturers to perform testing not specified in the
regulations in such circumstances. Thus, should we determine in the
future that such testing is needed, we would retain the authority to
require it pursuant to CAA section 208.
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    \575\ CARB intends to propose changes to their HD OBD program,
as mentioned in the CARB Workshop for 2020 OBD Regulations Update,
February 27, 2020. Available here: https://ww3.arb.ca.gov/msprog/obdprog/obd_feb2020wspresentation.pdf.
---------------------------------------------------------------------------

    EPA is proposing to retain our existing deficiency provisions in 40
CFR 86.010-18(n) and not harmonize with CARB's deficiency provisions in
13 CCR 1971.1(k).\576\ In the 2009 OBD rule, EPA stated that having a
deficiency provision is important ``because it facilitates OBD
implementation by allowing for certification of an engine despite
having a relatively minor shortfall,'' and that while the CARB OBD
regulations have a provision to charge fees associated with OBD
deficiencies, EPA has ``never had and will continue not to have any
such fee provisions.'' EPA is requesting comment on retaining our
existing deficiency requirements in its entirety or if any changes
should be made. EPA also seeks comment on how and for what reasons OEMs
have utilized CARB's deficiency policy, how this may impact compliance
with the new EPA and CARB requirements and how this may be impacted by
any future changes in OBD emission thresholds.\577\
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    \576\ We are proposing to migrate the existing deficiency
provisions of 40 CFR 86.010-18(n) into 40 CFR 1036.110(d).
    \577\ California Code of Regulations, Title 13, section
1971.1(k)
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    CARB's 2019 OBD update to 13 CCR 1971.1 also includes significant
changes applicable to hybrid vehicles. We are aware that current OBD
requirements necessitate close cooperation between engine and hybrid
powertrain system manufacturers for certification, which can present a
significant challenge for introducing heavy-duty hybrids into the
marketplace. To learn more about this potential challenge, EPA
requested input in the ANPR. We learned from commenters that no
manufacturers have pursued a certification flexibility that CARB put in
place in 2016 through the Innovative Technology Rule (ITR). The ITR
provided short-term certification flexibilities, such as allowing
hybrid manufacturers to use Engine Manufacturers Diagnostics (EMD),
rather than heavy-duty OBD for two to four consecutive model years
depending on the all-electric range of the
vehicle.578 579 580 We also heard from at least one hybrid
manufacturer suggesting that onboard NOX sensors could be
used in lieu of OBD for heavy-duty hybrids. The potential use of
onboard sensors to meet some OBD requirements for any heavy-duty
vehicle, including hybrids, is discussed in Section IV.C.2.ii below. We
continue to be interested in understanding from commenters and request
comment on whether and how OBD may present a barrier to the adoption of
heavy-duty hybrid systems, and any potential opportunities for EPA to
address such barriers. We have prepared a memorandum that further
explores these regulatory issues, with a discussion of a range of
possible options that we are considering for hybrid systems in heavy-
duty specialty vehicles, but which could apply more broadly to all
heavy-duty hybrid systems.\581\
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    \578\ Heavy-duty EMD requires diagnostic monitoring of the
performance and durability of the fuel system, exhaust gas
recirculation system (if so equipped), particulate trap, and other
emission-related electronic components.
    \579\ California Code of Regulations, Title 13, section 2208.1
    \580\ See the comments of the California Air Resources Board,
Docket ID EPA-HQ-OAR-2019-0055-0471.
    \581\ Stout, Alan. Memorandum to Docket EPA-HQ-OAR-2019-0055.
``Draft Amendments Related to Alternate Engine Standards for
Specialty Vehicles''. January 31, 2022.
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    Finally, EPA is seeking comment on whether improvements could be
made to OBD to monitor inducement conditions. For example, while
individual components responsible for inducements currently are
monitored (e.g., DEF level sensors), there is no requirement that
inducements themselves be monitored to ensure a false inducement did
not occur or that such events are tracked for remediation. EPA seeks
comment on whether OBD systems should monitor the inducement process
and detect system malfunctions prior to a failure (e.g., for
deterioration of the DEF delivery system) to improve emission system
performance by providing opportunities for repairs to be made prior to
complete failures and by preventing inducements that either should not
have occurred or could have been avoided.
iii. Additional OBD Provisions in the Proposed Federal Program
    EPA received comments on the ANPR from a wide variety of
stakeholders describing difficulties diagnosing problems with and
maintaining proper functionality of advanced emission technologies and
the important role accessible and robust diagnostics play in this
process. The California Air Pollution Control Officers Association and
NACAA commented on the need for EPA to develop and maintain a robust
OBD program with diagnostic specificity that would ensure OBD continues
to accurately detect system failures for lower emission standards and
inform the person performing the repair of what the problem is and the
cause, so it can be promptly, proficiently and cost-effectively
repaired, as well as to facilitate the development of comprehensive
enforcement programs.582 583 The Pennsylvania Department of
Environmental Protection commented that EPA should evaluate how
advances in OBD technology could be applied to enhance operations,
monitoring and maintenance capabilities of heavy-duty diesel
aftertreatment systems and how current and future technologies may use
OBD technologies to inform operators and repair technicians as to the
in-use efficacy of those systems across multiple duty cycles.\584\ ATA
commented that ease of diagnostics for emission component failures is a
significant concern for their members.\585\ NASTC members expressed
significant frustration with the inability to use existing diagnostics
to understand problems with emission components.\586\
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    \582\ See the comments of the California Air Pollution Control
Officers Association, Docket ID EPA-HQ-OAR-2019-0555-0275.
    \583\ See the comments of the National Association of Clean Air
Agencies, Docket ID EPA-HQ-OAR-2019-0055-0283.
    \584\ See the comments of The Pennsylvania Department of
Environmental Protection, Docket ID EPA-HQ-OAR-2019-0055-0455.
    \585\ See the comments of the American Trucking Association,
Docket ID EPA-HQ-OAR-2019-0055-0357.
    \586\ See the comments of the National Association of Small
Trucking Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
---------------------------------------------------------------------------

    As a part of our effort to update our OBD program and respond to
these concerns, EPA is proposing to include additional requirements as
well as modify certain CARB OBD requirements to better address newer
diagnostic methods and technologies and to ensure that OBD can be used
to properly diagnose and maintain emission control

systems to avoid increased real-world emissions. EPA intends to
continue to accept CARB OBD approval where a manufacturer can
demonstrate that the CARB program meets the intent of EPA OBD
requirements (see section IV.C.2.i.b. for further discussion), and
manufacturers would submit documentation as specified in proposed 40
CFR 1036.110(c)(5) to show that they meet the additional requirements
proposed here.
    In this section we describe the following proposed additional EPA
certification requirements in 40 CFR 1036.110 for OBD systems:
    1. Health monitors for the SCR, DPF, and EGR systems
    2. Display health monitor and inducement-related information in the
cab
    3. Diagnostic testing to measure the effectiveness of DEF dosing
must be made available for use with either a generic scan tool or an
equivalent alternative method
    Enhanced OBD systems that provide more information and value to the
operator can play an important role in ensuring expected in-use
emission reductions are achieved long-term. For example, in comments to
the ANPR, CARB stated that their test programs have identified numerous
heavy-duty vehicles with mileages within their applicable regulatory
useful life periods, but beyond their warranty periods, that had
NOX emission levels significantly above the applicable
certification standards.\587\ CARB also stated that some stakeholders
such as fleet owners, retrofit installers, and equipment operators have
communicated to CARB that they are experiencing significant vehicle
downtime due to parts failures.
---------------------------------------------------------------------------

    \587\ See the comments of the California Air Resources Board,
Docket ID EPA-HQ-OAR-2019-0055-0471.
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    Increasing the transparency and usefulness of OBD systems can help
to improve maintenance and repair experiences and also serve as a
mechanism to reduce owner frustration (which otherwise could provide
motivation to tamper). EPA is specifically proposing to improve the
robustness and usefulness of OBD systems by including emission system
health monitors, increasing the number of publicly available data
parameters, increasing the freeze frame data, and enabling certain
self-testing capabilities for owners. These changes will benefit the
environment by helping to reduce malfunctioning emission systems in-use
through access to additional data that may be useful for service
technicians, state and local inspection and maintenance operations, and
owners. These capabilities are also important to enable owners to avoid
potential inducement conditions that can result from certain component
failures.
a. Emissions Systems Health Monitor
    The purpose of OBD is to reduce motor vehicle and motor vehicle
engine emissions by monitoring the systems in-use, detecting
malfunctions, informing the operator, and assisting with diagnosis of
emission system problems. One concept EPA is proposing to incorporate
into our updated OBD regulations is the development of ``health
monitors'' for specific emission control technologies on CI engines to
provide vehicle owners information on the overall health of important
emissions systems at a given point in time. While OBD systems are
highly proficient in monitoring emission systems and components, the
historic purpose of OBD has been to monitor systems but only notify
operators generically (e.g., through the Malfunction Indicator Light or
``MIL'') once there is a failure or malfunction, rather than to use
monitored data to proactively provide the operator with information on
the functionality and status of such systems. However, existing OBD
monitors and data parameters could also be used in a different way to
generate aftertreatment health monitors. This could be accomplished by
evaluating data indicating how much a system has been used or how close
a system is to exceeding an OBD threshold. While most large fleets have
already begun to use similar measures by using big data and telematics
to implement predictive maintenance, this concept is different in that
it would be focused on using a particular vehicle's data to evaluate
system status as opposed to using data from thousands of trucks to
predict system status.\588\ Predictive maintenance relies on analytics
that examine existing data to identify potential risks of failure on
particular trucks or components prior to the failures occurring in the
field.\589\ Predictive maintenance can enable operators to replace
components later than when utilizing a traditional preventative
maintenance approach and can essentially increase the service life of
certain emission system components, prevent breakdowns, and reduce
total operating costs. Predictive maintenance could also result in
components being changed more frequently to avoid or reduce breakdowns
and downtime, thereby also reducing total operating costs. An emissions
system health monitor, while not as comprehensive of a tool as
predictive maintenance, could provide similar types of benefits
resulting in more uptime for emission control systems. Health monitors
could also provide critical insight on the status of a vehicle's
emissions systems for buyers considering purchasing used trucks. EPA is
proposing that the health monitors' status would need to be made
available on the dash or other display for access to the data without
the use of a scan tool. The purpose of the health monitor is not to
guarantee the performance of an emissions system in the future, but
instead to provide status information on the functioning of the
relevant system at the moment in time. In addition, such a monitor
could be used to warn users of potential upstream failures that can
cause damage to aftertreatment components resulting in expensive
repairs. EPA worked with Environment and Climate Change Canada
(``ECCC'') to develop this concept. Using an emissions system health
monitor to improve and make more efficient heavy-duty engine and
vehicle maintenance practices could provide environmental benefits by
helping to sustain system performance long-term.
---------------------------------------------------------------------------

    \588\ Park, Jim. September 7, 2018. ``How Data Is Changing
Predictive Maintenance.'' Available here: https://www.truckinginfo.com/312738/how-data-is-changing-predictive-maintenance.
    \589\ Lockridge, Deborah. May 31, 2019. ``How One Fleet is
Closing in on Predictive Maintenance.'' Available here: https://www.truckinginfo.com/332946/how-one-truck-fleet-is-closing-in-on-true-predictive-maintenance.
---------------------------------------------------------------------------

    In discussions with ECCC about how to develop a health monitor
concept, they suggested that a single value representing the
performance of the vehicle's emission system as a whole would be less
effective than two or three individual ``health monitors'', and EPA
agrees. EPA is proposing, and seeking comment on the benefits of,
specific methods for CI engines to inform a vehicle operator of the
general health of the DPF, SCR, and EGR systems. There are two main
approaches EPA could use to achieve this goal: (1) A broad requirement
that leaves the identification and implementation of the specific
methodologies up to each manufacturer, or (2) a specific requirement
that prescribes the methodologies to be used by all manufacturers. EPA
is proposing the first alternative, and seeks comment on the second
alternative, or any other alternative that commenters believe would be
more beneficial or less costly and that would still provide benefits to
the owner and resulting environmental benefits from better performing

emissions controls systems. Under any approach, we are interested in
emissions system health monitors that better enable owners to
understand emission system functionality, help avoid potential
breakdowns, and reduce incentives to tamper with emission control
systems as a result of experiencing unplanned and catastrophic emission
system failures. A prescriptive approach may be more useful in that it
would provide consistency between manufacturers which could result in
more useful and stable data for users, however, a broad requirement
that allows manufacturers to better capitalize on their existing OBD
system design may also achieve the goals of this health monitor
proposal. This proposal focuses on leveraging existing OBD requirements
in new ways to develop health monitors for DPF, SCR, and EGR systems to
avoid costs that could be associated with an entirely new monitoring
requirement. EPA seeks comment on whether additional monitors could be
developed utilizing existing OBD requirements which can further help
prevent downtime, such as additional upstream health indicators (e.g.,
preventing excessive internal oil leaks) to proactively prevent damage
to expensive aftertreatment components.

(1) Proposed DPF Health Monitor

    For the DPF system, EPA has identified essential information that
users should have access to for ensuring that proper maintenance and
use can occur. Having continuous access to DPF health information can
provide important insight on DPF system status. EPA is proposing that
users have access to the following information available for display in
the cab, which together would form the DPF health monitor: (1) A value
that indicates general system wear, for example a counter for the total
number of passive and active regeneration (``regen'') events that have
taken place on the existing DPF, (2) a value that indicates the average
active and passive regen frequency and a method for operators to track
changes in these values, (3) a value estimating (in miles or hours)
when the DPF needs to be cleaned to remove accumulated ash, and (4)
notification when active regens have been disabled by the system (even
temporarily) if accompanied by a derate, as well as the reason it was
disabled. While not specifically a part of the DPF health monitor, EPA
is proposing additional DPF maintenance information be made available
to users to improve serviceability experiences, see section IV.B.3.ii.
for more discussion on these proposed requirements.
    Providing users with a general indicator of system wear can help
users make informed maintenance decisions. EPA would expect that a
manufacturer would allow this monitor to be reset if a DPF is replaced.
Manufacturers could in part utilize work that may be done to meet CARB
OBD requirements to implement this proposal. For example, the 2019 CARB
OBD program that we are proposing to harmonize with includes a
provision for MY 2024 that requires a lifetime counter of DPF regens
(see 13 CCR 1971.1(h)(5.8.2)). EPA is seeking comment on the use of
CARB's required lifetime counter to meet this proposed requirement, or
what alternative information manufacturers could use to meet this
requirement and whether this information should be standardized.
    Providing users with an indication of the total average regen
frequency (active and passive) and with a method that could be used to
detect recent changes in system function can allow users to familiarize
themselves with proper system operation. For example, this could be
achieved by displaying the average regen frequency per a fixed number
of miles or hours and providing a resettable counter to show the most
recent average regen frequency. Such a feature would enable owners to
monitor the number of regens occurring over a particular route to
detect changes (e.g., a significant increase in the number of
regeneration events) which could inform them of the need to address
failures upstream of the DPF, clean the DPF, or service the DPF system.
In particular, EPA seeks to alert operators to potential conditions
that could indicate an upstream problem (e.g., an oil leak) that can
damage sensitive aftertreatment components prior to a catastrophic
failure or result in the need for costly repairs to aftertreatment
systems. Manufacturers may be able to utilize existing work already
being done to meet the frequent regeneration requirements in 13 CCR
1971.1(e)(8.2.2) to inform owners when regen frequency exceeds a
certain level that may indicate an upstream issue. As discussed
earlier, EPA is proposing that the health monitors' status would need
to be made available on the dash or other display for access to the
data without the use of a scan tool. EPA would expect that operators
would be able to access this information on demand, and that
manufacturers would not have the health monitor tied to the MIL to
avoid any confusion. EPA is seeking comment on whether this component
of the DPF health monitor is important enough to require that it be
communicated when the frequency of regens reaches a particular level
that may indicate the need for inspection and possibly repair, what
this level would be, and what such a warning system should look like.
    Having access to information that indicates an estimate of when the
DPF needs to be cleaned would allow operators to plan ahead for
critical maintenance and reduce downtime. We are not proposing a
specific method manufacturers would use to generate the estimated time
to perform such a cleaning, rather we would leave it to manufacturers
to determine the best method of implementation.
    Finally, providing operators with notification of when active
regens have been disabled by the system (even temporarily) as well as
the reason it was disabled would provide benefits to operators and
repair technicians. Manufacturers generally implement severe derates
when DPF system faults occur that prevent active regens from occurring.
Providing owners with information on the cause of a DPF-related derate
would reduce frustration and may reduce downtime by allowing repairs to
be made more quickly, increasing in-use emission system performance.
    EPA is seeking comment on how manufacturers could lessen the
effects of duty cycle related regens frequency variability in the
health monitor (e.g., vehicles that operate more at lower speeds would
likely experience more active regens than those that operate at higher
steady-state speeds), through normalizing the reported data or focusing
on specific regions of operation where regens occur with more
regularity. For example, this DPF health monitor parameter could
include only passive regens that occur during certain vehicle
operation, such as operation that occurs in OBD REAL Bin 14. EPA is
seeking comment on whether the DPF health monitor should provide this
information on demand, and if it should also notify users of potential
concerns.
(2) Proposed SCR Health Monitor
    For the SCR system, EPA has identified essential information that
users should have access to for ensuring that proper preventive
maintenance occurs. EPA is proposing that the SCR health monitors'
status would need to be made available on the dash or other display for
access to the data without the use of a scan tool. Having access to SCR
health information on demand can provide important insight on SCR
system status and help operators prevent inducements from occurring.
EPA is proposing that users have access to the following information
for the SCR

health monitor: (1) Indicator of average DEF consumption and a method
for operators to track changes in this value, (2) warnings before
blockages in the DEF line or dosing valve actually occur and an
inducement would be triggered, and (3) information on when DEF dosing
has been disabled by the system (even temporarily) if accompanied by a
derate as well as the reason it was disabled. EPA is not proposing
specific methods manufacturers would use to meet these requirements and
would be leaving it up to manufacturers to develop the most appropriate
method based on their product designs. We are taking comment on this
approach, or if instead we should specify the way the SCR health
monitor should be implemented, which would ensure consistency across
the fleet.
    Providing users with an indication of average DEF consumption and
with a method that could be used to detect recent changes in that value
can allow users to familiarize themselves with proper system operation.
This could be achieved for example by manufacturers providing the
lifetime average DEF used per gallon of fuel and a recent or resettable
counter to show the most recent average DEF consumption value. Such a
feature would enable owners to develop a high-level understanding of
proper SCR function and operation, can alert the operator to changes
that may indicate a problem before there is a failure resulting in a
breakdown and corresponding downtime, and enable owners to monitor the
data over a particular route (or after a particular repair) to detect
system changes (or evaluate the effectiveness of a recent repair).
    EPA is seeking comment on how manufacturers could lessen the
effects of duty cycle related DEF consumption variability in the health
monitor, through normalizing the reported data or focusing on specific
regions of operation where DEF consumption should be more stable. For
example, this SCR health monitor parameter could include provide
average DEF consumption that occurs during certain vehicle operations,
such as operation that occurs in OBD REAL Bin 14.
    The SCR health monitor proposal also includes a requirement for
manufacturers to provide information to the operator regarding
potential plugging of the DEF line or dosing valve prior to a blockage
actually occurring. Manufacturers have likely developed strategies to
monitor such blockages in response to EPA's existing inducement
guidance.590 591 DEF can crystallize over time and build up
in SCR components such as the injector, which in some cases could also
result in a false inducement being triggered for conditions that appear
to be caused by tampering, which this health monitor can help
prevent.\592\ Further, it is critical to ensuring that DEF restrictions
are promptly addressed to maintain proper SCR system function. Finally,
EPA is proposing that the health monitor provide information on when
DEF dosing has been disabled by the system (even temporarily) as well
as the reason it was disabled if accompanied by a derate. Having access
to this information is critical to ensuring operators can perform
maintenance timely, and potentially prior to a vehicle going into
inducement. EPA is seeking comment on whether the SCR health monitor
should provide this information on demand, and if it should also notify
users of potential concerns.
---------------------------------------------------------------------------

    \590\ See CISD-09-04 REVISED.
    \591\ See Section IV.D.4. for further discussion on proposed
inducement-related requirements for blocked DEF lines.
    \592\ For example, see NHTSA Service Bulletin available here:
https://static.nhtsa.gov/odi/tsbs/2019/MC-10153679-9999.pdf.
---------------------------------------------------------------------------

    Finally, EPA is seeking comment on alternative methods to develop a
health monitor for SCR systems, for example including one that would
use DEF dosing trim values (i.e., DEF dosing rates at particular
operating points such as within NTE operating zones or REAL bins) and
compare the dosing rate that is occurring in real-time to what the
dosing rate was when the vehicle was new. The idea is that as
components wear and SCR performance deteriorates, the system may
compensate by increasing the DEF dosing rate at a particular operating
point; using the information contained in the engine controller
software could help alert operators to such changes and allow them to
perform repairs or maintenance prior to the vehicle experiencing a
catastrophic failure. This method, especially if combined with ammonia
slip information, could offer a better indication of system
performance.
(3) Proposed EGR Health Monitor
    For the EGR system, EPA has identified essential information that
users should have access to for ensuing proper maintenance and use can
occur. In particular, we expect access to information indicating EGR
valve coking or EGR cooler failure, which are the two main failure
conditions, may avoid devastating impacts on downstream aftertreatment
components.593 594 We are proposing to require manufacturers
to provide an indication of EGR valve health. For example, they could
use existing OBD signals to provide an indication of the health of an
EGR valve by looking at the difference between commanded and actual EGR
valve position to indicate valve coking. The intent of this health
monitor is to enable operators to understand when the EGR valve is
becoming plugged and allow them to perform preventative maintenance
prior to a catastrophic failure.
---------------------------------------------------------------------------

    \593\ Anderson, Jeremy. 2017 presentation at American Public
Transportation Association 2017 Annual Meeting & EXPO. Titled ``DPF
Maintenance: Avoid the Five Most Common Mistakes.'' Available here:
https://www.apta.com/wp-content/uploads/Resources/mc/annual/previous/2017annual/LZpresentations/Learning%20Zone%20Presentations/Anderson,%20Jeremy.pdf.
    \594\ Stanton, Bob. April 4, 2017. ``Aftertreatment System: A
New System Not to be Overlooked.'' Available here: https://www.worktruckonline.com/157340/aftertreatment-system-a-new-system-not-to-be-overlooked.
---------------------------------------------------------------------------

    In addition, EPA is proposing a health monitor for the EGR cooler.
Manufacturers could in part utilize work already being done to meet
existing CARB requirements in 13 CCR 1971.1(e) for EGR cooler
performance monitoring to satisfy this requirement. These requirements
specify that manufacturers design their system to monitor the cooler
system for insufficient cooling malfunctions, including the individual
electronic components (e.g., actuators, valves, sensors). The OBD
system must detect a malfunction of the EGR cooler system prior to a
reduction from the manufacturer's specified cooling performance that
would cause an engine's NMHC, CO, or NOX emissions to exceed
2.0 times any of the applicable standards or the engine's PM emissions
to exceed the applicable standard plus 0.02 g/hp-hr. EPA is seeking
comment on these or other strategies that can help inform operators of
the functionality of the EGR system to help prevent breakdowns due to
EGR system failures, including whether or how to monitor for EGR cooler
leaks or plugging, such as through the use of pressure or temperature
sensors, and whether today's engines are equipped with sensors in the
EGR system that could be used for this purpose. We are also seeking
comment on whether fault codes related to incidents of engine derate
due to EGR-related failures should be displayed in the cab as a part of
this health monitor, similar to what is being proposed for SCR and DPF-
related derate issues.

b. Expanded List of Public OBD Parameters
    In another area for improvement in the OBD program, EPA proposes to
harmonize with the revised list of data parameters CARB has developed
for MY 2024 through our incorporation by reference of CARB's revised
OBD regulations and to further expand the list of OBD parameters that
manufacturers are required to make publicly available. 13 CCR
1971.1(4.2) data stream requirements state that the listed signals be
made available on demand through the ``standardized data link
connector'' (OBD port) in accordance with J1979/J1939 specifications.
The requirements also specify that the actual signal value must be
used, the default or limp home value cannot be used. Until MY 2024,
CARB regulations require a list of 91 signals that must be made
publicly available, of which approximately ten are related to
aftertreatment and primarily include measures of the pressure and
temperature of the DPF. CARB updated these requirements in 2019 such
that additional aftertreatment-related signals will be added in MY 2022
and MY 2024. EPA is proposing to adopt CARB's parameter list through
our incorporation by reference of their updated 2019 OBD regulations,
to add signals to the list, and to specifically require the addition of
all parameters related to fault conditions that trigger vehicle
inducement to be made readily available using generic scan tools if the
engine is so equipped (see Section IV.D for more discussion on
inducements). EPA would expect that each of these additional
requirements would need to be addressed even where manufacturers relied
in part on a CARB OBD approval to meet the intent of our proposed OBD
regulations. The purpose of including additional parameters is to make
it easier to identify malfunctions of critical aftertreatment related
components, especially where failure of such components would trigger
an inducement. In addition, the proposed additional information can
make the repairs themselves easier by allowing for immediate access to
fault codes, which could alleviate the long wait times associated with
specialized emission repair facilities or where facilities are not
available when an inducement occurs (such as on the weekend or in a
remote location). In response to the ANPR, EPA received comments
supportive of such changes, for example from the National Tribal Air
Association (``NTAA'') who noted that service information and tools
should be made easily available and affordable for individual owners to
diagnose and fix their own vehicles, which can be especially important
for small businesses, Tribes, and those in rural areas with less ready
access to original equipment manufacturer dealer networks.\595\
---------------------------------------------------------------------------

    \595\ See comments of the National Tribal Air Association,
Docket ID EPA-HQ-OAR-2019-0555-0282.
---------------------------------------------------------------------------

    We are proposing a general requirement to make such parameters
available if they are used as the basis for an inducement response that
interferes with the operation of the engine or vehicle. For example, if
the failure of an open-circuit check for a DEF quality sensor leads to
an engine inducement, the owner/operator would be able to identify this
fault condition using a generic scan tool. This proposal should be
enabled in part by a change to the comprehensive component monitoring
requirements in CARB's 2019 OBD regulations. CARB now specifies that
for MY 2024 and later, comprehensive component monitoring must include
any electronic powertrain component/system that either provides input
to (directly or indirectly) or receives commands from an on-board
computer or smart device, which is also used as an input to an
inducement strategy or other engine derate (see 13 CCR
1971.1(g)(3.1.1)). We are also proposing some new parameters for HD SI
engines, as mentioned in Section III.D.2. We are proposing that
manufacturers make additional parameters available for all engines so
equipped, including:
     For Compression Ignition engines:
    [cir] Inlet DOC and Outlet DOC pressure and temperature
    [cir] DPF Filter Soot Load (for all installed DPFs)
    [cir] DPF Filter Ash Load (for all installed DPFs)
    [cir] Engine Exhaust Gas Recirculation Differential Pressure
    [cir] DEF quality
    [cir] Parking Brake, Neutral Switch, Brake Switch, and Clutch
Switch Status
    [cir] Aftertreatment Dosing Quantity Commanded and Actual
    [cir] Wastegate Control Solenoid Output
    [cir] Wastegate Position Commanded
    [cir] DEF Tank Temperature
    [cir] Injection Control Pressure Commanded and Actual
    [cir] DEF System Pressure
    [cir] DEF Pump Commanded Percentage
    [cir] DEF Coolant Control Valve Control Position Commanded and
Actual
    [cir] DEF Line Heater Control Outputs
     For Spark Ignition Engines:
    [cir] A/F Enrichment Enable flags: Throttle based, Load based,
Catalyst protection based
    [cir] Percent of time not in stoichiometric operation (including
per trip, and since new)
    [cir] Catalyst or component temperature parameters (measured and
modeled, if applicable) specifically used for thermal protection
control strategies as proposed in Section III.D.2.
    EPA is seeking comment on whether any additional signals should be
included in this list to help ensure in-use emission benefits occur as
expected, and whether any other signals should be included such as any
signals related to maintenance derates (outside of inducements).
Although CARB currently requires a list of signals that must be made
public, EPA encountered difficulty accessing many of these signals in
recent testing on in-use trucks. EPA, working closely with Environment
and Climate Change Canada, used a number of generic scan tools on a
variety of vehicle makes and models and were unable to see all of the
publicly required data. While this could indicate a problem with a
specific generic scan tool design, none of the scan tools from a range
of price points was able to display the complete set of signals; some
tools read less than a third of the required signals. Some parameters
read ``No Response'' or ``Not Available'' or were missing a signal in
its entirety. This situation can cause frustration for owners who own
generic scan tools and are unable to access any required data when
trying to repair vehicles. EPA requests comment on operator experiences
with obtaining data using generic scan tools from trucks in-use.
c. Expanding Freeze Frame Data Parameters
    One of the more useful features in the CARB OBD program for
diagnosing and repairing emissions components is the requirement for
``freeze frame'' data to be stored by the system. To comply with this
requirement, manufacturers must capture and store certain data
parameters (e.g., vehicle operating conditions such as the
NOX sensor output reading) within 10 seconds of the system
detecting a malfunction. The purpose of storing this data is in part to
record the likely area of malfunction. CARB has identified a list of
approximately 63 parameters that must be captured in the freeze frame
data for gasoline engines and 69 parameters for diesel engines.
Currently, the freeze frame data does not include additional signals
for aftertreatment systems. While existing CARB freeze frame data
requirements include some DPF-related parameters (e.g., inlet and
outlet pressure and temperature), there is essentially no SCR
information, which

EPA believes is essential for proper maintenance. We are therefore
proposing that EPA's updated OBD requirements include the additional
parameters proposed in section IV.C(1)(ii)(b) of this preamble and
those included in the following section of CARB's regulations sections
13 CCR 1971.1(h)(4.2.1)(D), 1971.1(h)(4.2.2)(H), 1971.1(h)(4.2.3)(F),
1971.1(h)(4.2.3)(G), 1971.1(h)(4.2.2)(I). We welcome comment on this
proposal, including whether additional data parameters should be
included in the freeze frame data to enable those diagnosing and
repairing vehicles to more effectively identify the source of the
malfunction and increase the usefulness of freeze frame data,
especially for conditions that result in inducement.
d. System Commanded Tests To Facilitate Inducement-Related Diagnoses
and Repairs
    Today's vehicle control systems have built-in tests that can be
used to command components to perform a particular function in order to
confirm that they are working properly.\596\ An equally important
element of an effective OBD program is ensuring owners have the ability
to run certain engine or vehicle tests and view the results, especially
where they can be used by owners in diagnosing and repairing problems
that may result in inducement. If, for example, the problem was caused
by a faulty DEF pump, this type of repair likely does not require
specialized training to complete but is difficult to detect without
access to such a test. More immediate diagnosis and repair of faulty
components such as this would result in reduced costs for owners and
increased long-term environmental benefits through improved emission
control function.
---------------------------------------------------------------------------

    \596\ Morgan, Jason. January 21, 2019. ``What the right data can
tell you about aftertreatment issues.'' Available here: https://www.fleetequipmentmag.com/heavy-duty-truck-aftertreatment-service-issues-data/.
---------------------------------------------------------------------------

    Today, vehicle software scan tools can be designed to command a DEF
pump to operate, which allows a person diagnosing a DEF injection issue
to measure how much DEF is pumped during a certain time interval and
compare this amount to the specifications to determine whether or not
the pump and injector are functioning properly. Performing the test
would allow diagnosis of the vehicle and a quick determination of
whether the DEF pump is working, the DEF injector is not faulty, there
are no wiring-related issues, and DEF is being sprayed properly (both
in terms of amount and spray pattern). Due to the importance of the DEF
pump in maintaining full functionality of a vehicle (i.e., avoiding
inducement), EPA is proposing that the DEF dosing test be made
available for use with either a generic scan tool (be made available on
demand through the OBD port in accordance with J1979/J1939
specifications) or an alternative method (e.g., an option commanded
through a vehicle system menu).
    Another important test that is used today is an SCR performance
test that some OEMs offer through their proprietary scan tools. This
type of test causes the diagnostic system to run the engine through a
specific operating cycle to check certain SCR parameters, providing a
pass/fail result and indicating what potential problems may exist. In
particular, this test allows for a repeatable method to be used to
compare a known set of engine operating parameters and SCR performance
specifications to verify that SCR performance is as-expected and to
narrow the scope of any existing problems that need to be fixed. There
are currently non-OEM scan tools that also can conduct the same test,
but the engine's diagnostic system may not allow the generic scan tool
to access the pass/fail results. The results of this test could be
especially helpful for users or technicians, may help avoid unexpected
breakdowns, and may improve in-use emissions. Running an SCR
performance test can enable the owner or technician to monitor system
parameters during the test (e.g., by watching SCR inlet and outlet
temperatures during a particular operating cycle) to evaluate if
certain components are functioning properly during the test and may
reduce the need for regens to be run instead, which can reduce wear on
the DPF system. We are requesting comment on whether EPA should make
SCR performance tests available via generic scan tool or other on-
vehicle method. EPA is also requesting comment on the need to make
other self-tests accessible with generic scan tools to improve in-use
emission systems maintenance and performance, for example being able to
command that the evaporative system on SI engines be sealed to allow
for leak testing or including the ability to perform manual regens for
DPF systems.
2. Other OBD Provisions
    In addition to our proposal to update our OBD regulations by
incorporating much of the CARB OBD program by reference, we are also
requesting comment on other improvements to our OBD program. The
improvements would be intended to make the program more effective at
improving maintenance of in-use engines and vehicles, as well as
reducing the compliance burdens for manufacturers. We welcome comments
suggesting other ways to improve our OBD program.
i. OBD Provisions From the Recent HD Technical Amendment Rule
    EPA recently revised our OBD regulations to harmonize with certain
CARB requirements in our HD Technical Amendments (HDTA) rulemaking (86
FR 34340, June 29, 2021). This rule finalized four updated OBD
provisions including: (1) Revising the misfire threshold, (2) adopting
updated misfire flexibilities, (3) revising our in-use minimum ratios,
and (4) allowing the use of CARB OBD reporting templates for EPA OBD
requirements. EPA did not take final action at that time on two
proposed revisions related to OBD demonstration testing and carry-over
of OBD certification. The following sections summarize the revisions
previously proposed and the concerns expressed in
comments.597 598
---------------------------------------------------------------------------

    \597\ See 85 FR 28152, May 12, 2020.
    \598\ EPA, ``Improvements for Heavy-Duty Engine and Vehicle Test
Procedures, and other Technical Amendments Response to Comments,''
December 2020, Docket EPA-HQ-OAR-2019-0307, Publication Number: EPA-
420-R-20-026 (see discussion starting on page 80).
---------------------------------------------------------------------------

a. Demonstration Testing Requirements
    One of the provisions EPA did not take final action on in the HDTA
rulemaking was related to determining the number of engines required to
undergo demonstration testing. The existing requirements of 40 CFR
86.010-18(l) and 13 CCR 1971.1(l) specify the number of test engines
for which a manufacturer must submit monitoring system demonstration
emissions data. Specifically, a manufacturer certifying one to five
engine families in a given model year must provide emissions test data
for a single test engine from one engine rating, a manufacturer
certifying six to ten engine families in a given model year must
provide emissions test data for a single test engine from two different
engine ratings, and a manufacturer certifying eleven or more engine
families in a given model year must provide emissions test data for a
single test engine from three different engine ratings.
    The HDTA proposed rulemaking (85 FR 28152, May 12, 2020) proposed
to allow CARB certified configurations to not count as separate engine
families for the purposes of determining OEM demonstration testing
requirements for

EPA OBD approval. EPA received adverse comment on this proposal stating
that it was inconsistent for EPA to not include CARB-only families when
determining demonstration testing requirements for 49-state EPA
families, but to accept demonstration test data from CARB-only families
to meet 49-state EPA certification. There were additional concerns that
the proposal did not include the criteria that EPA would use to approve
or deny the request to not count certain families, and that this
proposal applied to ``special families'' which were not defined by EPA.
In the HDTA final rulemaking, EPA explained that this provision
required additional consideration and did not take final action on it
at that time.
    We stated in the HDTA final rulemaking that we intended to review
this issue as a part of the HD 2027 proposal. EPA recently issued
guidance for certain cases, where an OBD system designed to comply with
California OBD requirements is being used in both a CARB proposed
family and a proposed EPA-only family and the two families are also
identical in all aspects material to expected emission characteristics.
EPA anticipates that a manufacturer would be able to demonstrate to EPA
that the intent of 40 CFR 86.010-18(l) is met for the EPA-only family
by providing proof that CARB has determined the monitoring system
demonstration requirements for the corresponding CARB proposed family
have been met.\599\ We are proposing to codify this as a provision in
40 CFR 1036.110(b)(11). We are requesting comment on this provision,
including whether additional restrictions should be included to ensure
engine families are appropriately counted. EPA is also seeking comment
on allowing a similar provision for cases where equivalent engine
families differ only in terms of inducement strategies (see section
IV.D.6 for further discussion). Finally, EPA is seeking comment on
whether we should include revisions beyond those proposed to address
this situation.
---------------------------------------------------------------------------

    \599\ EPA Guidance Document CD-2021-04 (HD Highway), April 26,
2021, ``Information on OBD Monitoring System Demonstration for Pairs
of EPA and CARB Families Identical in All Aspects Other Than
Warranty.'' Available here: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=52574&flag=1.
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b. Use of CARB OBD Approval for EPA OBD Certification
    EPA did not take final action on the proposed reordering of 40 CFR
86.010-18(a)(5) in the HDTA final rulemaking. These existing EPA OBD
regulations allow manufacturers seeking an EPA certificate of
conformity to comply with the federal OBD requirements by demonstrating
to EPA how the OBD system they have designed to comply with California
OBD requirements also meets the intent behind federal OBD requirements,
as long as the manufacturer complies with certain certification
documentation requirements. EPA has implemented these requirements by
allowing a manufacturer to submit an OBD approval letter from CARB for
the equivalent engine family where a manufacturer can demonstrate that
the CARB OBD program has met the intent of the EPA OBD program. In
other words, EPA has interpreted these requirements to allow OBD
approval from CARB to be submitted to EPA for approval.
    We are proposing to migrate the language from 40 CFR 86.010-
18(a)(5) to 40 CFR 1036.110(a) to allow manufacturers to continue to
use a CARB OBD approval letter to demonstrate compliance with federal
OBD regulations for an equivalent engine family where manufacturers can
demonstrate that the CARB OBD program has met the intent of the EPA OBD
program. In the case where a manufacturer chooses not to include
information showing compliance with additional EPA OBD requirements in
their CARB certification package (e.g., not including the additional
EPA data parameters in their CARB certification documentation), EPA
would expect manufacturers to provide separate documentation along with
the CARB OBD approval letter to show they have met all EPA OBD
requirements. This process would also apply in the case where CARB has
further modified their OBD requirements such that they are different
from but meet the intent of existing EPA OBD requirements. For example,
if CARB finalizes the use of a different communication protocol than
EPA's requirements call for, as long as it meets the intent of EPA's
communication protocol requirements (e.g., can still be used with a
generic scan tool to read certain parameters), the proposed process
would apply. EPA expects manufacturers to submit all documentation as
is currently required by 40 CFR 86.010-18(m)(3), detailing how the
system meets the intent of EPA OBD requirements, why they have chosen
the system design, and information on any system deficiencies. As a
part of this update to EPA OBD regulations, we are clarifying in 40 CFR
1036.110(c)(4) that we can request that manufacturers send us
information needed for us to evaluate how they meet the intent of our
OBD program using this pathway. This would most often mean sending EPA
a copy of documents submitted to CARB during the certification process.
c. Potential Use of the J1979-2 Communications Protocol
    In a February 2020 workshop, CARB indicated their intent to propose
allowing the use of Unified Diagnostic Services (``UDS'') through the
SAE J1979-2 communications protocol for heavy-duty OBD with an optional
implementation as early as MY 2022.600 601 CARB stated that
engine manufacturers are concerned about the limited number of
remaining undefined 2-byte diagnostic trouble codes (``DTC'') and the
need for additional DTCs for hybrid vehicles. J1979-2 provides 3-byte
DTCs, significantly increasing the number of DTCs that can be defined.
In addition, this change would provide additional features for data
access that improve the usefulness of generic scan tools to repair
vehicles.
---------------------------------------------------------------------------

    \600\ SAE J1979-2 was issued on April 22, 2021 and is available
here: https://www.sae.org/standards/content/j1979-2_202104/.
    \601\ CARB Workshop for 2020 OBD Regulations Update, February
27, 2020. Available here: https://ww3.arb.ca.gov/msprog/obdprog/obd_feb2020wspresentation.pdf.
---------------------------------------------------------------------------

    Section IV.C.1. of this preamble asks for comment on whether EPA
should harmonize with any updated CARB OBD amendments finalized prior
to the issuing of this final rulemaking; however, it is not clear if
CARB's amendment including UDS would be finalized in time for EPA to
include it in this final rule. We will monitor the development of the
CARB OBD update and are seeking comment on whether we should finalize
similar provisions if CARB does not finalize their update before we
complete this final rule. CARB is expected to allow the optional use of
the J1979-2 protocol as soon as MY 2023. If manufacturers want to
certify their engine families for nationwide use, we would need to
establish a process for reviewing and approving manufacturers' requests
to comply using the alternative communications protocol. While we
support adoption of J1979-2 and are clarifying and proposing pathways
to accommodate its use, we are seeking comment on potential challenges
associated with this change.
    While EPA believes our existing requirements in 40 CFR 86.010-
18(a)(5) allow us to accept OBD systems using J1979-2 that have been
approved by CARB, there may be additional considerations prior to the
finalization of this rule for OEMs that want to obtain

a 49-state certificate for engines that do not have CARB OBD approval.
For model years prior to MY 2027, since our proposed OBD revisions
would take effect in MY 2027 if finalized, EPA is proposing to include
interim provisions in 40 CFR 1036.150(v) to allow the use of J1979-2
for manufacturers seeking EPA OBD approval. Finally, once EPA's
proposed updated OBD requirements would be in effect for MY 2027, we
expect to be able to allow the use of J1979-2 based on the proposed
language in 40 CFR 1036.110(b). We are seeking comment on these
pathways to approval and on whether any additional changes need to be
made to our existing or proposed OBD requirements to accommodate the
use of J1979-2.
    While there are expected environmental benefits associated with the
use of this updated protocol, we are seeking comment on whether the use
of this alternative protocol could have negative impacts on our
existing OBD program. In addition to potential impacts on EPA's OBD
program, EPA is seeking comment on any potential impacts this change
could have on our service information requirements (see Section
IV.B.3.ii. for more background on these provisions). CAA section
202(m)(4)(C) requires that the output of the data from the emission
control diagnostic system through such connectors shall be usable
without the need for any unique decoding information or device, and it
is not expected that the use of J1979-2 would conflict with this
requirement. Further, CAA section 202(m)(5) requires manufacturers to
provide promptly to any person engaged in the repairing or servicing of
motor vehicles or motor vehicle engines, and the Administrator for use
by any such persons, with any and all information needed to make use of
the emission control diagnostics system prescribed under this
subsection and such other information including instructions for making
emission related diagnosis and repairs. Manufacturers who choose to
voluntarily use J1979-2 as early as MY 2022 would need to provide
access to systems using this alternative protocol at that time and meet
all of the relevant requirements in 40 CFR 86.010-18.
    EPA believes that the software and hardware changes needed to
accommodate J1979-2 are minimal, and that these changes would not
impact an OEM's ability to make vehicle data available at a fair and
reasonable cost. We seek comment on how tool vendors would be affected,
whether they would be able to support the new services and data
available in J1979-2, and if there are any concerns tool manufacturers
have regarding access to vehicle data at a fair and reasonable cost.
    While the move to UDS has been discussed by OEMs in the past with
CARB, a proposal was expected to be released last year, but is now
expected this year, and while SAE is working on a new standard, J1978-2
to specify the scan tool requirements to interface with J1979-2, this
standard is not yet available.602 603 EPA is seeking comment
on the impact to generic scan tool manufacturers of the timing of the
voluntary allowance for the use of J1979-2 in MY 2023 and whether scan
tool manufacturers can provide updated tools for use to diagnose and
repair vehicles as well as for inspection and maintenance facilities in
time for MY 2023, or if this protocol should not be allowed for use
until a later model year and if so what the appropriate timing is.
Specifically, EPA is seeking comment on the following issues related to
generic scan tools:
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    \602\ IM Solutions, IM Solutions OBD Communication Update
Webinar, June 10, 2020. Available here: https://www.obdclearinghouse.com/Files/viewFile?fileID=2239.
    \603\ SAE, J1978-2 available here: https://www.sae.org/standards/content/j1978-2/.
---------------------------------------------------------------------------

     Will vendors be able to meet the MY 2023 timeframe?
     Can existing tools be updated to accommodate the new
protocol or do new scan tools need to be developed to utilize J1979-2?
     Will any additional hardware changes be required to
accommodate J1979-2?
     Do tool vendors expect the price of tools that can utilize
J1979-2 to be comparable to tools that utilize J1979?
     Do state inspection and maintenance facilities require
additional time to be able to modify or update equipment to handle
J1979-2?
     Will generic scan tools be able to read both J1979-2 and
J1979 or will separate tools be required?
     Will generic scan tool functionality be the same or better
with the implementation of J1979-2?
     Will users require specialized training to use J1979-2
tools?
     Is development going to be delayed until the adoption of
SAE J1978-2?
ii. Use of Tailpipe Emission Sensors
    EPA is seeking comment on whether and how to allow manufacturers to
use onboard emission sensors to help reduce test burden associated with
OBD certification. In particular, EPA would like comment on ways to
reduce test cell time associated with component threshold testing, such
as ways to use NOX sensor data instead of test cycle
NOX measurements (provided those sensors meet the proper
specifications). There are further complications for testing outside of
a test cell to demonstrate compliance that need careful consideration
(as it is assumed that testing that relies on onboard NOX
sensors would happen outside of a test cell), including:
     What alternative testing methods are reasonable and would
provide assurances that they are creating robust diagnostic systems?
     For what operating conditions and over what time frame
should this testing occur?
     What NOX values should be considered (e.g.,
average NOX over a certain period of time, or for a
particular set of operating conditions?)
     What ambient and vehicle operating conditions should be
considered?
     How can this methodology ensure repeatable results?
     How would EPA verify this methodology for compliance
assurance?
    This type of strategy could potentially reduce compliance costs
because it would reduce the amount of emission testing manufacturers
need to perform in a test cell during OBD development. We request
comment on this and other aspects of the OBD program that could be
improved through the use of emissions sensors. EPA is also seeking
comment on alternative methods to use onboard emission sensors that
could be used to generate and provide real-world data that may enable
improved diagnostics, assess the function of emissions critical
components and assess the implementation of dynamic AECD inputs. Such a
program could be voluntary and provide additional data that could be
used in the future to analyze whether changes to the OBD program should
be made to improve compliance demonstrations and reduce test cell
burden.
3. Cost Impacts
    Heavy-duty engine manufacturers currently certify their engines to
meet CARB's OBD regulations before obtaining EPA certification for a
50-state OBD approval. We anticipate most manufacturers would continue
to certify with CARB and that they would certify to CARB's 2019 updated
OBD regulations well in advance of the EPA program taking effect;
therefore, we anticipate the incorporation by reference of CARB's 2019
OBD requirements would not result in any additional costs. EPA does not
believe the additional OBD requirements described here would result in
any significant costs, as there are no requirements for new monitors,
new data parameters, new hardware, or new

testing included in this rule. However, EPA has accounted for possible
additional costs that may result from the proposed expanded list of
public OBD parameters and expanded scan tool tests in the ``Research
and Development Costs'' of our cost analysis in Section V. EPA
recognizes that there could be cost savings associated with reduced OBD
testing requirements; however, we did not quantify the costs savings
associated with proposed changes to the CARB's OBD testing
requirements. We seek comment on our approach to including costs for
OBD and the savings associated with each proposed OBD testing
modification.

D. Inducements

1. Background
    The 2001 final rule that promulgated the criteria pollutant
standards for MY 2010 and later heavy-duty highway engines included a
detailed analysis of available technologies for meeting the new
emission standards.\604\ Manufacturers ultimately deployed urea-based
SCR systems instead of catalyzed particulate traps and NOX
absorbers as EPA had projected in 2001. SCR is very different from
these other emission control technologies in that it requires operators
to maintain an adequate supply of diesel exhaust fluid (DEF), which is
generally a water-based solution with 32.5 percent urea. Operating an
SCR-equipped engine without the DEF would cause NOX
emissions to increase to levels comparable to having no NOX
controls at all.
---------------------------------------------------------------------------

    \604\ 66 FR 5002, January 18, 2001; see Section I of the
preamble for more information on the history of emission regulations
for this sector.
---------------------------------------------------------------------------

    As manufacturers prepared to certify their SCR-equipped engines to
the EPA 2010 standards, EPA was concerned that operators might not take
the necessary steps to maintain a supply of DEF to keep the emission
controls working properly. To address concerns regarding the design and
operation of SCR-equipped heavy-duty highway diesel engines and
vehicles, between 2007 and 2012 EPA published three guidance documents,
two notices and one request for comment in the Federal Register, and
participated in a joint public workshop with CARB.\605\ These documents
focused on the following three main categories of relevant regulatory
requirements in the context of the use of DEF in SCR-equipped engines:
(1) Critical emissions-related scheduled maintenance requirements, (2)
adjustable parameters requirements, and (3) auxiliary emission control
device (AECD) requirements. The EPA guidance identify possible
approaches to meeting these regulations for heavy-duty diesel engines
using SCR systems; however, the approaches were not required to be used
and EPA explained that no determination was made in the guidance on
whether the engine and vehicle designs that use the approaches are
acceptable for certification, since that determination must be made
based on the design of particular engines or vehicles. We broadly refer
to this engine derate guidance as an inducement policy and design
strategy. Throughout this preamble we refer to engine derates that
derive from DEF-related triggers as ``inducements.'' This section
discusses the relevant prior development and use of an inducement
policy and design strategy for heavy-duty highway vehicles and engines,
including comments we received on operators' experiences with
inducements under that strategy in our Advanced Notice of Proposed
Rulemaking, principles for updating inducement approaches for heavy-
duty highway vehicles and engines, and proposed inducement provisions
for heavy-duty highway vehicles and engines.\606\
---------------------------------------------------------------------------

    \605\ Kopin, Amy. Memorandum to Docket: EPA-HQ-OAR-2019-0055.
Inducement-Related Guidance Documents and Workshop Presentation,
October 1, 2021.
    \606\ See 85 FR 3306.
---------------------------------------------------------------------------

i. DEF Replenishment as Critical Emissions-Related Scheduled
Maintenance
    EPA regulations at 40 CFR 86.004-25 limit the emission-related
scheduled maintenance that may be performed by manufacturers for
purposes of durability testing and specify criteria for inclusion in
manufacturers' maintenance instructions provided to purchasers of new
motor vehicles and new motor vehicle engines. Of particular relevance
here, the regulations in 40 CFR 86.004-25(a)(2) specify that
maintenance performed on vehicles, engines, subsystems, or components
used in the determination of emission deterioration factors is
classified as either emission-related or non-emission-related, and
either scheduled or un-scheduled. Emission-related scheduled
maintenance must be technologically necessary to assure in-use
compliance with the emission standards and must meet the specified
allowable minimum maintenance intervals, as provided in 40 CFR 86.004-
25(b) (including cross-referenced 40 CFR 86.094-25(b)(7)).\607\
Additionally, to ensure that emission controls used in the durability
demonstration do not under-perform in-use as a result of vehicle owners
failing to perform scheduled maintenance, manufacturers must show that
all critical emission-related scheduled maintenance have a reasonable
likelihood of being performed in-use (see 40 CFR 86.004-25(b)(6)(ii)).
---------------------------------------------------------------------------

    \607\ See Section IV.B.5 for our proposal to migrate and update
the maintenance provisions from 40 CFR 86.004-25 and 86.010-38 to 40
CFR 1036.125.
---------------------------------------------------------------------------

    In the guidance document CISD-07-07 signed on March 27, 2007, EPA
stated that the use of DEF is consistent with the definition of
critical emission-related maintenance and therefore these requirements
would apply to the replenishment of the DEF tank. EPA stated that
manufacturers wanting to use SCR technology would likely have to
request a change to scheduled maintenance requirements per 40 CFR
86.094-25(b)(7), as the existing minimum maintenance intervals were
100,000 miles for medium-duty and 150,000 miles for heavy-duty diesel
engines. Following the completion of the guidance, EPA received several
requests for new maintenance intervals for SCR-equipped motor vehicles
and motor vehicle engines. EPA granted these requests for model years
2009 through 2011 for heavy-duty engines in a notice that was published
in the Federal Register (74 FR 57671, November 9, 2009). Engine and
vehicle manufacturers provided additional requests for new maintenance
intervals for vehicles and engines in model years not covered by the
November 9, 2009 Federal Register notice.
    In the November 9, 2009 Federal Register notice and the guidance
document CISD-09-04-REVISED (CISD-09-04R), regarding the requirement
that manufacturers must show that all critical emission-related
scheduled maintenance have a reasonable likelihood of being performed
in-use, the document explained that manufacturers could make such a
showing by satisfying at least one of the conditions listed in the
then-applicable 40 CFR 86.094-25(b)(6)(ii)(A-F). In particular, the
guidance focused on two of the methods in the regulation: (1)
Presenting information establishing a connection between emissions and
vehicle performance such that as emissions increase due to lack of
maintenance the vehicle performance will deteriorate to a point
unacceptable for typical driving; and (2) installing a clearly
displayed visible signal system approved by EPA to alert the driver
that maintenance is due. In the CISD-09-04R guidance, EPA identified
possible approaches to show a reasonable likelihood that DEF in a
vehicle's tank will be maintained at acceptable levels.

    For the first method, CISD-09-04R suggested that performance that
deteriorates to a point unacceptable for typical driving would be
sufficiently onerous to discourage operation without DEF. EPA suggested
in CISD-09-04R that a possible approach could be for the manufacturer
to include a derate of the engine's maximum available engine torque of
a sufficient magnitude for the operator to notice decreased operation,
explaining that a derate of at least 25 percent is likely to be needed
for such an effect, and a progression to further degradation to
severely restrict operation. For the second method, CISD-09-04R
suggested that a clearly displayed visible signal system could include
a DEF level indicator, messages in the instrument cluster, a DEF
indicator, engine shutdown lamp, or audible warnings to warn the driver
that maintenance is due (DEF refill is needed). The CISD-09-04R
guidance reiterated that these are possible general approaches to meet
the requirement that the critical maintenance is reasonably likely to
occur in use, but EPA will evaluate all approaches taken by
manufacturers at the time of certification, and such evaluation will be
based on the requirements in the regulations.
    On January 5, 2012 (77 FR 488), EPA updated and extended its
approval of maintenance intervals for the refill of DEF tanks for
heavy-duty engines for 2011 and later model years. In a separate
rulemaking in 2014, EPA added DEF tank size (which dictates DEF
replenishment rate) to the list of scheduled emission-related
maintenance for diesel-fueled motor vehicles and motor vehicle engines
in 40 CFR 86.004-25(b)(4)(v).\608\ We are proposing to migrate this
provision into new 40 CFR 1036.115(i).
---------------------------------------------------------------------------

    \608\ 79 FR 46356, August 8, 2014. ``Emergency Vehicle Rule--SCR
Maintenance and Regulatory Flexibility for Nonroad Equipment.''
---------------------------------------------------------------------------

    EPA also added a limitation in 40 CFR 86.004-25(b)(5)(ii) for DEF
replenishment (a critical emission-related scheduled maintenance item),
requiring that manufacturers must satisfy paragraph (b)(6)(ii)(A) or
(F) to be accepted as having a reasonable likelihood of the maintenance
item being performed in-use. EPA explained that the criteria in
(b)(6)(ii)(B)-(E) were not sufficiently robust for DEF replenishment,
and therefore would not be sufficient for demonstrating that DEF
replenishment is reasonably likely to occur in use. We are proposing
that the proposed inducement requirements in 40 CFR 1036.111 will
ensure the reasonable likelihood of DEF replenishment being performed
in-use. EPA is not proposing any changes to DEF refill intervals. We
are proposing to exclude the alternative option in (b)(6)(ii)(F) to
demonstrate DEF replenishment is reasonably likely to be performed in-
use, but are seeking comment on whether this provision should instead
be preserved. EPA is otherwise proposing to migrate the provisions in
40 CFR 86.004-25(b)(5)(ii) to 40 CFR 1036.125(a)(1) (section IV.D.3.
describes the proposal in detail).
ii. DEF as an Adjustable Parameter
    EPA regulations in 40 CFR 86.094-22(e) require that manufacturers
comply with emission standards over the full adjustable range of
``adjustable parameters'' and state that we will determine the adequacy
of the limits, stops, seals or other means used to inhibit
adjustment.\609\ For any parameter that has not been determined to be
adequately limited, 40 CFR 86.094-22(e) authorizes the Administrator to
adjust the parameter to any setting within the physical limits or stops
during certification and other testing. In determining the parameters
subject to adjustment, EPA considers the likelihood that settings other
than the manufacturer's recommended setting will occur in-use,
considering such factors as, but not limited to, the difficulty and
cost of getting access to make an adjustment; damage to the vehicle if
an attempt is made; and the effect of settings other than the
manufacturer's recommended settings on engine performance. Adjustable
parameters historically included things like physical settings that are
controlled by a dial or screw.
---------------------------------------------------------------------------

    \609\ Section XII.A.2 describes how we are proposing to update
regulatory provisions in 40 CFR 1068.50 related to adjustable
parameters.
---------------------------------------------------------------------------

    In guidance document CISD-07-07, EPA provided clarification that an
SCR system utilizing DEF that needs to be periodically replenished
would meet the definition set forth in paragraphs 40 CFR 86.094-
22(e)(1) and 86.1833-01(a)(1) and could be considered an adjustable
parameter by the Agency. EPA is confirming that DEF is considered an
adjustable parameter because it is both physically capable of being
adjusted and significantly affects emissions. In particular, DEF level
and quality are parameters that can physically be adjusted and may
significantly affect emissions. SCR system designs rely on storing DEF
in a tank located on the vehicle, the operator refilling the tank with
quality DEF, and quality DEF being available. This design depends on
the vehicle operator being made aware that DEF needs to be replaced
through the use of warnings and vehicle performance deterioration. The
EPA guidance CISD-07-07 described that without a mechanism to inform
the vehicle operator that the DEF needs to be replaced, there is a high
likelihood that the adjustable parameter will be circumvented or
exceeded in-use and therefore EPA would not consider the system to be
adequately inaccessible or sealed. EPA stated in CISD-07-07 that we
would not prescribe a specific driver inducement design, but that the
options identified in the guidance could be utilized to demonstrate
that the driver inducement design was robust and onerous enough to
ensure that engines will not be operated without DEF in the vehicle
(e.g., if the operator ignored or deactivated the warning system). In
addition, the guidance stated that the driver inducement mechanism
should not create undue safety concerns, but should make sure vehicle
operators are adding DEF when appropriate by having the vehicle
performance degraded in a manner that would be safe but would be
onerous enough to discourage vehicles from being operated without DEF.
EPA stated that the key challenge of this approach is to determine what
would constitute an acceptable performance degradation strategy.
    EPA guidance document CISD-09-04R re-emphasized that under the
adjustable parameter requirements, EPA makes a determination at
certification whether the engine is designed to prevent operation
without quality DEF. The guidance suggested a similar strategy for both
DEF level and quality could be used, which would alert the operator to
the problem and then use a gradually more onerous inducement strategy
to either fill the tank or correct the poor-quality DEF and discourage
its repeated use. CISD-09-04R also provided more detail on the
potential use of inducements with tamper resistant designs to reduce
the likelihood that the adjustable parameters will be circumvented in
use, noting that in particular, manufacturers should be careful to
review the tamper resistance of the system to prevent the disconnection
of certain components (e.g., DEF pump or dosing valve). EPA did not
determine in CISD-07-07 what specific amount of time or mileage would
be necessary for an inducement policy. EPA guidance document CD-13-13
was issued in November 2013 in response to concerns that operators may
dilute DEF with water to reduce

costs.\610\ CD-13-13 provides guidance to manufacturers of heavy-duty
on-highway engines on how EPA expects to determine the physical range
of adjustment of DEF quality for certification testing. EPA explained
that we generally would consider the range of adjustment for emission
testing to span the change in urea concentration from 32.5 percent
(unadulterated DEF) to the point at which poor DEF quality can be
detected. This guidance also provides possible measures manufacturers
may take, such as inducements, to sufficiently restrain the adjustment
of DEF quality to limit the need for testing outside the manufacturer's
specified range. EPA is proposing to adopt certain performance
degradation strategy requirements that must be met for EPA to make a
determination at certification that the engine is designed to prevent
operation without quality DEF under the adjustable parameter
requirements (section IV.D.3. describes the proposal in detail).
---------------------------------------------------------------------------

    \610\ Kopin, Amy. Memorandum to Docket: EPA-HQ-OAR-2019-0055.
Inducement-Related Guidance Documents, and Workshop Presentation,
October 1, 2021.
---------------------------------------------------------------------------

iii. DEF Usage and Auxiliary Emission Control Devices (AECDs)
    In CISD-09-04R EPA discussed that under extreme temperature
conditions DEF may freeze and not immediately flow to the SCR system.
There are, however, systems and devices that can be utilized to ensure
the flow of DEF. These systems are evaluated as AECDs (see 40 CFR
86.082-2) and manufacturers must describe this AECD and show that the
engine design does not incorporate strategies that reduce emission
control effectiveness compared to strategies used during the applicable
Federal emissions test procedures. EPA examines systems during
certification for ensuring proper dosing during extreme conditions such
as cold weather operation. CISD-09-04R provided an example of a test
procedure that could be used for ensuring the SCR system has adequate
DEF freeze protection. Under this example, SCR systems that are capable
of fully functional dosing at the conclusion of the test procedure
might be considered acceptable. EPA is not proposing any changes to
existing regulatory requirements for AECDs or to supersede guidance
with our proposed requirements, if finalized, except as explicitly
identified in section 40 CFR 1036.111.
iv. Tamper-Resistance Design
    The existing EPA guidance and this section discuss inducements as a
tamper-resistant design strategy in the context of steps manufacturers
can take to prevent operation without quality DEF. Under the CAA,
engines must meet emission standards promulgated under section 202(a)
throughout useful life. Engines that do not meet those standards
throughout useful life may result in increased emissions that
fundamentally undermine EPA's emission control program and prevent us
from realizing the intended improvements in air quality. Tamper-
resistant design in engines can be an important part of a
manufacturer's compliance strategy to ensure that emissions standards
are met in-use throughout useful life. In addition to the reasons
described in the cited guidance documents, an inducement strategy for
SCR-system tamper-resistance can be part of a manufacturer's
demonstration at certification that engines will be built to meet
emission standards in-use throughout useful life.
    The Agency believes that combining detection of open-circuit fault
conditions for SCR components (i.e., disconnection of SCR components)
with inducements would decrease the likelihood that the SCR system will
be circumvented through tampering.
2. ANPR Comments on the EPA's Inducement Guidance
    The ANPR requested comment on EPA's existing guidance related to
SCR and DEF. A majority of the comments expressed concern that despite
the use of high-quality DEF and in the absence of tampering, in-use
vehicles are experiencing inducements for reasons outside of the
operator's control. Commenters stated that the reasons for these types
of inducements are often difficult to diagnose and can lead to repeat
trips to a repair facility and additional costs. Commenters also stated
that the existing schedule and speeds are not necessary to achieve
EPA's compliance goals, and instead the severe nature of these concerns
may be leading to unusual tampering rates. This section summarizes the
submitted comments.
    Several commenters described problems with repeated occurrences of
inducements even with the use of a sufficient quantity of high-quality
DEF and in the absence of tampering (i.e., a ``false inducement'').
They reported that some of these cases were traceable to incidents
where the system detected a problem that did not exist and did not
create emission concerns, for example a vehicle with a full DEF tank
experienced an inducement due to a faulty DEF level sensor which
reported an empty tank. Commenters stated that false inducements can
occur, for example, as a result of software glitches, wiring harness
problems, minor corrosion of terminals, or faulty sensors, even if
those problems have no effect on the function of the emission control
system.\611\
---------------------------------------------------------------------------

    \611\ For example, see the comments of the National Association
of Small Trucking Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
---------------------------------------------------------------------------

    Commenters stated that ``no trouble found'' events were common
where repair technicians were unable to diagnose a system fault after
the engine triggered an inducement. This condition has also been
documented by manufacturers who have issued technical service bulletins
(``TSBs'') discussing such concerns. EPA has identified a significant
number of TSBs documenting in-use problems that cause erratic fault
codes which can lead to inducements or engine derate despite operators
using high-quality DEF and not tampering.\612\ For example, some TSBs
describe faulty wire harness routing problems that can cause
inducements and recommend fixes that include adding extra zip ties or
tape. Commenters noted that erratic system problems can lead to
``defensive repairs'' as a diagnostic strategy for returning the
vehicle to service, which could result in repair expenses for replacing
parts that are not faulty and add risk of future costs if the problem
reoccurs, repeated tows are required, further diagnosis is done, and
more repairs are attempted. Commenters expressed a particular concern
for intermittent fault conditions that make diagnosis especially
difficult. To alleviate such concerns, ATA commented that EPA should
eliminate inducements for reasons other than maintaining an adequate
supply of high-quality DEF. ANPR commenters also expressed a concern
that technicians might repair a defective part without addressing the
root problem that caused the part to fail, which again leads to
repeated experiences of towing and repairing to restore an engine to
proper functioning.
---------------------------------------------------------------------------

    \612\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``TSB Aftertreatment Faults.'' September 9, 2021.
---------------------------------------------------------------------------

    Commenters stated that, despite their continued diligence to use
high-quality DEF, they have repeated experiences with inducements
resulting in very onerous costs. Some commenters noted they were
subject to the most severe restrictions multiple times per year even
though DEF tanks were properly filled.

OOIDA commented that inducement-related costs can severely jeopardize
owner-operators' ability to stay in business, citing costs that
included towing and lost income from downtime in addition to diagnosis
and repair. Commenters were especially concerned with long-distance
routes, which might involve a vehicle that is several days distant from
the base of operations. Other commenters highlighted that service
information and tools should be made easily available and affordable
for individual owners to diagnose and fix their own vehicles, which can
be important for small businesses, Tribes, and those in rural areas
with less ready access to original equipment manufacturer dealer
networks.\613\ While these comments did not specifically discuss
inducements, EPA also considers these comments relevant to vehicles
that are in an inducement condition. Other commenters added that false
inducements in these situations can necessitate having engines serviced
at an unfamiliar repair facility that has no information on a given
vehicle's repair history, which can result in improper repairs and
increased travel expenses for drivers to return home.\614\
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    \613\ For example, see the comments of the Keweenaw Bay Indian
Community, Docket ID AX-20-000-3862.
    \614\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``ANPR Inducement Comment Summary.'' August 5, 2021.
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    Commenters stated that the four hours of operation before engines
reach final inducement is poorly matched with typical wait times of
three or four days before repair technicians can look at and attempt to
diagnose the problem with their vehicles, plus additional time is
needed to complete the repairs. Commenters further stated that repair
technicians are often unable to diagnose the problem, repairs can take
several days in any case, with additional time lost if there is a need
to order parts and wait for shipment, and there are frequently ``come-
back'' repairs for vehicles not fixed properly the first time.
    Commenters stated that the money needed for a tow would be better
spent on repairs.\615\ Some commenters emphasized that a speed
restriction of 5 mph caused the need for towing, even though a less
restrictive inducement would accomplish the same purpose without
incurring towing expenses.
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    \615\ Commenters suggested the cost of a tow starts at $800,
which could approximately cover the cost to replace a faulty
NOX sensor. Others noted that the cost of a tow and
related repairs is estimated to be around $7500-8000.
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    Commenters described experiences of sudden inducements restricting
vehicle speed to 5 mph which they stated caused highway safety problems
for truck drivers and nearby vehicles.\616\ Others described having
safety concerns when a vehicle is stranded, such as having buses
carrying passengers parked along the highway or freeway.\617\
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    \616\ For example, see the anonymous comments in Docket ID EPA-
HQ-OAR-2019-0055-0426.
    \617\ See the comments of Theilen Bus Lines, Docket ID EPA-HQ-
OAR-2019-0055-0521.
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    Some commenters stated that in addition to monetary costs, there
are other business impacts such as missing critical deadlines, loss of
customer trust and credibility, and loss of future contracts. Other
comments indicate that EPA's existing inducement policy, especially
where application of it has resulted in false inducements, may have
created a strong incentive to either tamper with SCR systems (e.g.,
installing ``delete kits'') and may be leading to owners extending the
life of older vehicles; they further asserted that these behaviors were
causing trucks to fail to accomplish the intended emission reduction
goal. For example, the American Truck Dealers division of National Auto
Dealers Association commented that in addition to emission-related
maintenance and repair issues, improperly functioning SCR derate
maintenance inducements have also led to emissions tampering.\618\
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    \618\ See the comments of the National Automotive American Truck
Dealers division of National Auto Dealers Association, Docket ID
EPA-HQ-OAR-2019-0055-0369.
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    It is worth noting that in comments on CARB's Omnibus rule both the
California Trucking Association and ATA member companies requested CARB
work with EPA to further investigate the efficacy of progressive de-
rate inducements typically associated with low-volume or empty DEF
tanks or the use of poor-quality DEF. They added that the safety and
environmental implications of these types of de-rate occurrences need
additional evaluation and study prior to enacting additional
NOX controls. Further, they commented that following more
than a decade of experience, de-rates not related to low DEF levels or
inferior DEF quality continue to occur, and that among a sampling of
fleets operating more than 10,000 trucks, nearly 80 percent of de-rates
in 2019 were attributed to other causes such as sensor failures,
electrical defects and SCR component issues. ATA stated that many of
these causes are not associated with the emissions performance of the
SCR system and yet are initiating operational restrictions. After the
ANPR was issued, EPA received a letter from charter bus companies
detailing their concerns and difficulties experienced with existing
inducements. Specifically, they mentioned the inadequate timeframe for
which to resolve problems, the safety risk to passengers, the high cost
of towing, other costs incurred due to breakdowns such as
reimbursements owed for tickets to missed shows or flights, and the
cost to their reputation despite their efforts to maintain their fleets
and keep the emissions systems functioning properly.\619\
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    \619\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055.
``Letter to EPA from Bus and Motorcoach Operators Regarding
Inducement Experiences In-Use.'' November 17, 2021.
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3. Principles for Updating Inducement Provisions
    In general, emission control technology is integrated into engine
and vehicle systems in ways that do not require routine operator
interaction. However, ensuring that on-highway engines using SCR are
designed, consistent with our regulations, to prevent operation without
quality DEF through and dependent upon steps performed by operators in-
use presents unique challenges. Crafting an inducement policy includes
complex technological questions on how manufacturers should demonstrate
that SCR system standards and related requirements will be met and
challenging policy decisions on how to appropriately motivate or
restrict certain types of human behavior that are either necessary for
or directly impact in-use compliance with emissions standards. EPA
recognizes and commenters have highlighted that the existing inducement
policy and its implementation have resulted in a complex mix of
incentives and behaviors. Policymaking for inducements therefore
presents itself not as an engineering problem with a single solution.
    EPA is proposing to codify inducement provisions, which include
adjustments as compared to our existing inducement guidance after
consideration of manufacturer designs and operator experiences with
SCR. We recognize that SCR technology has continued to mature, and
appropriate designs for heavy-duty engines using SCR systems have
evolved over the past decade. EPA continues to believe that designing
SCR-equipped engines with power derating is an effective and reasonable
measure to ensure that operators perform critical emissions-related
scheduled maintenance on the SCR system and to demonstrate to EPA that
it is reasonable to anticipate, consistent with requirements for

adjustable parameters, that the engine would normally be operated using
quality DEF. We are proposing inducement requirements whose objective
is to ensure that emission controls function and emission reductions
occur in-use while reducing potential impacts to operators through the
consideration of the following key principles.
    EPA's inducement approach should result in:
    1. Operators maintaining an adequate supply of high-quality DEF
while discouraging tampering of SCR systems,
    2. a speed derating schedule for inducement that balances impacts
to operators while still achieving required emission control,
    3. unique inducement schedules for different categories of vehicles
that reflect different primary operating conditions to ensure that the
final inducement speed is effective while acknowledging operating
constraints,
    4. ensuring that the inducement condition is warranted,
    5. clear communication of SCR system problems to the operator,
    6. avoiding the need for intervention at a dealer or other
specialized service center where possible, and
    7. reduced likelihood of in-use tampering based on a more targeted
inducement approach.
    Development of regulatory inducement requirements that reflect
these key principles requires consideration of potentially competing
concerns. A minimally restrictive approach might result in increased
emissions because of extensive operation without scheduled maintenance
being performed and circumvention of the limit on the adjustable range
(i.e., without use of sufficient high-quality DEF). In contrast, an
overly restrictive approach might impose unnecessary costs and pose a
threat to operators' livelihoods, as well as leading to potentially
increased tampering with engines or reduced fleet turnover rates that
would lead to increased emissions.
    The principles described here are those EPA used to develop the
proposed inducement provisions in 40 CFR 1036.111 and are discussed
later in this section for heavy-duty engines certified under 40 CFR
part 1036 that use SCR systems. These principles are based on our
existing guidance but include important adjustments. The first
principle is to develop an effective inducement proposal that ensure
that all critical emission-related scheduled maintenance has a
reasonable likelihood of being performed and allows manufacturers to
demonstrate an acceptable performance degradation strategy at the time
of certification to meet adjustable parameter requirements. This
principle should result in a proposal that would ensure operators will
add high-quality DEF and would help prevent tampering with the SCR
system by requiring increased levels of inducement to occur in stages
for reasons related to insufficient quantity of high-quality DEF or
tampering with the SCR system. This approach creates an immediate and
increasing incentive to remedy the problem. Operators would keep tanks
full of high-quality DEF prior to the inducement process starting and
avoid tampering with the SCR system.
    Our second principle seeks to identify an appropriate speed
derating schedule for inducements that reflects experience gained over
the past decade with SCR. This schedule would better balance impacts to
operators while ensuring that all critical emission-related scheduled
maintenance has a reasonable likelihood of being performed and allow
manufacturers to demonstrate an acceptable performance degradation
strategy at the time of certification to meet adjustable parameter
requirements. An appropriate inducement speed and schedule should be
low enough to ensure that operators maintain a supply of high-quality
DEF, while allowing engines to operate at a limited speed over a
restricted timeframe that restricts commercial operation (e.g., highway
operation) but allows for safely operating the vehicle to return home
for repair and to perform the necessary post-repair diagnostic checks
to avoid ``come-back'' repairs. Almost all heavy-duty vehicles are
engaged in commercial activity for which it would be completely
unacceptable to operate indefinitely at vehicle speeds that do not
allow for travel on limited-access highways. This principle should
result in an inducement schedule that would allow a reduced level of
operation over a sufficient period of time for operators when there is
a need to get a driver home from a distance, deliver critical freight
(e.g., passengers, livestock, or concrete) or for scheduling repairs in
a time or area of limited openings in repair shops. Establishing an
inducement policy that would be consistent among manufacturers would
improve operator experiences. For example, today manufacturer
strategies may differ in ways that potentially may have significant
effects on operators (e.g., some manufacturers implement a final severe
inducement only after a vehicle is stopped, others implement it
immediately while a vehicle is in motion). EPA believes another
important aspect of this principle is to set an inducement schedule
that would include additional stages of derated engine power that would
be tied to drive-time to create a predictable schedule of increasing
incentive to repair the engine. We also believe that our proposed
approach, including the proposed inducement speeds and schedules, would
be the most effective way to minimize operational disruptions due to
potential supply chain problems such as component or DEF shortages.
    The third principle is to recognize the diversity of the real-world
fleet and that one inducement schedule may not be appropriate for the
entire fleet. Instead, separate inducement speeds and schedules should
apply to vehicles that primarily operate at low- or high-speeds to
ensure an appropriate final inducement is applied. Certain vocational
vehicles, such as utility trucks, local delivery vehicles, refuse
trucks, cement mixers, and urban buses do not operate fast enough to be
effectively constrained by the same inducement speed that would be
appropriate for trucks with extended highway driving. Similarly,
applying a low final inducement speed to the entire fleet would overly
constrain vehicles that spend the majority of their time at highway
speeds. Rather than the EPA identifying a different inducement schedule
for each type of vehicle, vehicles would be subject to an alternative
inducement schedule based on the average vehicle speed history recorded
in the onboard computer.
    The fourth principle would not apply an inducement if there is a
fault code flagged by the system but the SCR system is still
controlling NOX emissions. Under this principle, putting a
vehicle into an inducement for a condition that does not result in a
failure of the engine to comply with emission standards would be
inconsistent with the goal of an inducement policy. To apply
inducements consistent with this principle, manufacturers would design
their diagnostic system to override a detected fault condition if
NOX sensors confirm that the SCR system is in fact
appropriately reducing NOX emissions. The diagnostic system
depends on multiple sensors and complex algorithms to detect fault
conditions. This override feature could be helpful to reduce false
inducements that can occur when the fault is not due to tampering or
the absence of high-quality DEF in the system (e.g., a faulty DEF level
sensor in a tank full of DEF). An inducement approach that includes a

backup check would address problems with faulty sensors or part
shortages that can strand owners.\620\ Under CARB's updated 2019 OBD
regulations, which apply under CARB's regulations starting with MY 2023
compliant OBD systems would be able to query data in the most recent
``active 100-hour array'', which monitors and records the most recent
engine and emission control parameters at discrete operating conditions
to confirm that appropriate NOX reductions are occurring. We
are proposing to incorporate by reference these updated CARB OBD
requirements and to make them mandatory for MY 2027 and later, while
manufacturers could voluntarily choose to certify to these requirements
prior to that (see section IV.C.1. for further discussion on OBD).
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    \620\ July 10, 2021. De Maris, Russ, ``Will a DEF head problem
ruin your trip?'' Available here: https://www.rvtravel.com/def-head-problem-ruin-trip/.
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    The fifth principle seeks to improve the type and amount of
information operators receive from the truck to help avoid or quickly
remedy a problem that is causing an inducement. This could include
manufacturers providing information on the dashboard or other display
to indicate when the first (and next) stage of derating will start in
addition to identifying the current (and next) restricted speed. It is
important for operators to understand what is happening to the truck as
well as whether or not they can make it back home or to a preferred
repair facility and reduce anxiety that can occur when an inducement or
engine derate occurs. The indicator would also show the fault condition
that caused the inducement. This status information would help to
prevent an unsafe condition resulting from an unexpected step down in
speed, and it would give operators important information for planning
routes to arrange for repairs.
    The sixth principle includes allowing operators to perform an
inducement reset by using a generic scan tool or allowing for the
engine to self-heal through the completion of a drive cycle that will
warm up the SCR system to operating temperature and permit the system
to automatically reset the inducement condition as appropriate. This
approach would allow vehicle owners much more discretion to perform
repairs themselves or select appropriate repair facilities for their
vehicles. This flexibility becomes increasingly important as vehicles
get older, especially for second or third owners, who typically depend
on simpler maintenance procedures to keep operating costs low enough
for viable operation. Any system reset that does not follow the fault
condition being addressed would require the engine to immediately
return to the stage of inducement that applied before the reset, which
would address the risk of improper resets. Together with allowing more
time to diagnose and repair a vehicle, this provision would help to
address comments from Tribal interests stating that Tribes and others
operating in remote areas often have limited access to dealers or
specialized repair facilities for repairing engines including vehicles
that are in an inducement condition. These provisions would increase
options available to all vehicle owners and small fleets who perform
their own repair and maintenance and may be unable to service their own
vehicles if the fault condition occurs any distance from the home base.
A higher proposed final inducement speed would also allow the OBD
system to run an internal diagnostic check to confirm that the fault
condition is no longer active and that the SCR catalyst is again
reducing NOX emissions. This would be especially important
for vehicle owners that do their own repair work on older vehicles or
for operators in remote areas with limited access to dealers and
specialized tools.
    The seventh principle seeks to develop an inducement schedule that