Malfunction Indicator Lamp: Description and Operation

The Malfunction Indicator Lamp (MIL) alerts the driver that the Powertrain Control Module (PCM) has detected an OBD II emission-related component or system fault. When this occurs, an OBD II Diagnostic Trouble Code (DTC) will be set.
^ The MIL is located on the instrument panel and is labeled SERVICE ENGINE SOON.
^ Power is supplied to the MIL whenever the ignition switch is in the RUN or START position.
^ The MIL will remain on in the RUN/START mode as a bulb check or until the CKP signal is detected.
^ The light may also be on due to a short to ground of the MIL circuit.
^ An engine, with federal calibration, operating in the Failure Mode Effects Management (FMEM) will cause the MIL to be on.
^ To turn off the MIL after a repair, a clear code command from the Scan Tool must be sent.
^ For any MIL concern, go to Symptom Charts. Symptom Related Diagnostic Procedures