Malfunction Indicator Lamp

Malfunction Indicator Lamp (MIL):

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.

When a fault has been detected in two consecutive drive trips, a DTC will be stored in the PCM and the MIL will be turned ON. The MIL will be turned OFF after three consecutive trips have been completed without the same fault being detected. The DTC will be erased from keep alive Random Access Memory (RAM) after 40 warm-ups without the fault being detected, except for misfire or fuel injection system DTCs which will be erased after 80 warm-ups without a fault being detected. The only exception to this is if a misfire occurs that could cause damage to the catalyst. In that event, the MIL will be turned ON immediately or may flash.

The MIL is located on the dashboard and is labeled "CHECK ENGINE" or "SERVICE ENGINE SOON." Power is supplied to the MIL whenever the ignition switch is in the run or crank position. The MIL will remain ON in the run/crank mode as a bulb check until the Camshaft Position (CMP) signal is detected. The light may also be ON due to a short to ground of the MIL circuit, or operation in the fail safe mode. In addition, the MIL will remain ON if the MIL was ON when the vehicle was last shut down. If the MIL does not turn OFF while the engine is cranking, it could indicate the PCM is not receiving the CMP signal or the MIL circuit is shorted to ground. If the MIL blinks, there is a severe misfire or an intermittent in the MIL circuit.

To extinguish the MIL after a repair, a reset command from the scan tool must be sent, or three consecutive drive cycles must be completed without a fault.