P0118 - Engine Coolant Temperature Sensor Circuit High Input

Description and meaning of DTC p0118

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to all 1996-newer vehicles (Honda, Toyota, Volkswagen VW, Mazda, Dodge, Ford, BW, etc. ). Although generic, the specific repair steps may vary depending on make/model. The engine coolant temperature (ECT) sensor is a thermistor screwed into acoolant passage in the cylinder head. Sensor resistance is high when coolanttemperature is low and resistance drops when coolant temperature increases. The powertrain control module (PCM) provides a 5 volt reference and a groundto the sensor. The PCM monitors voltage drop to determine coolant temperature. If the ECT reads less than freezing temp. when engine has been running for morethan a few minutes, the PCM determines a circuit fault and sets this code. Orif the PCM determines the sensor resistance is out of specs, this code is set.

p0118 diagnostic trouble code symptoms

Symptoms of a P0118 could include:Very poor fuel economy A no start condition Vehicle may start, but run very poorly, blowing black smoke, running veryrough and misfiring Illumination of MIL

DTC p0118 - possible causes

A code P0118 may mean that one or more of the following has happened:A bad connection at the sensor An open in the ground circuit between the ECT sensor and the PCMA short in the voltage feed between the sensor and the PCM A bad PCM (less likely) A bad temperature sensor (shorted internally)

How to fix OBD-II diagnostic trouble code p0118

First, if you have access to a scan tool, check the reading of the coolantsensor. Does it read a logical number? If so, the problem is likely intermittent. Perform a wiggle test by wiggling the connector and harness to thesensor while watching the reading on the scan tool. Watch for any drop-outs. Drop-outs would indicate a bad connection. If the scan tool reads an illogicaltemperature, check the resistance of the temperature sensor. If it is out ofspecs, replace it. If it is in specifications, unplug the sensor and, usinga fused jumper wire, jumper the two terminals of the connector together. Thetemperature reading should now be maxed out to above 250 degrees F. If not,there is likely a problem with the ground circuit or voltage supply. Check for 5 volts reference voltage at the connector. Also check for groundpresence at the connector. If you do not have 5V ref. and/or ground continuity,check for these back at the PCM connector. If you have these at the PCM connector,then repair open or short between the PCM and the sensor. If you do not, removethe offending wire from the PCM and then check for proper voltage at the PCMpin. If it's present now, repair short on the circuit. If it isn't present afterremoving the wire and checking the pin, replace PCMNOTE: Usually, P0118 is indicative of a bad temperature sensor, but doesn'trule out these other possibilities. If you're unsure of how to diagnose a PCM,do not attempt. Other engine coolant engine light codes: P0115, P0116, P0117, P0118, P0119, P0125, P0128

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