Malfunction Indicator Light

The Malfunction Indicator Light (MIL) is located on instrument panel and is labeled CHECK ENGINE. MIL will illuminate if PCM detects a failure of an OBD-II emission related component. When this occurs, a DTC will be set into PCM memory.

When a malfunction has been detected in 2 consecutive drive cycles, PCM will turn on MIL and store a DTC in memory. If same malfunction is not detected for 3 consecutive drive cycles, PCM will turn MIL off. DTC will remain in Keep Alive Memory (KAM) for 40 drive cycles, then DTC will be purged from PCM memory. One exception is if a misfire malfunction is detected that may damage catalytic converter, MIL will illuminate or flash immediately and DTC will be set.

If MIL remains on during engine cranking, it could indicate PCM is not receiving a signal from Camshaft Position (CMP) sensor or MIL circuit is shorted to ground. If MIL blinks, there may be a severe misfire being detected by PCM. To turn MIL off after a repair, a PCM reset command from scan tool must be sent, or 3 consecutive drive cycles must be completed without any detected malfunction.