Malfunction Indicator Light

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

When PCM detects an emission related DTC during first drive cycle, DTC and engine data are stored in freeze frame memory. MIL is illuminated only when PCM detects the same emission related DTC after it occurs in 2 consecutive trips. After MIL is illuminated, it will only turn off after PCM detects 3 trips without any faults occurring. One exception is if a misfire malfunction is detected that may damage catalytic converter. In this case the MIL will illuminate or flash immediately and DTC will be set. Misfire malfunctions will stay in Keep-Alive Memory (KAM) for 80 warm-up cycles. DTCs that would cause vehicle emissions to exceed established limits are capable of illuminating MIL during first trip. These include misfire, catalyst, and closed loop control DTCs. To turn MIL off after a repair, a PCM reset command from the scan tool must be sent, or 3 consecutive drive cycles must be completed without any detected malfunction.