Malfunction Indicator Light

Malfunction Indicator Light (MIL) displays on instrument cluster as CHECK ENGINE. OBD-II requires that MIL be illuminate under a strict set of guide lines. MIL is turned on when PCM detects a DTC that will impact vehicle emissions. MIL is under control of the Diagnostic Executive. MIL will be illuminated if an emissions-related diagnostic test indicates a malfunction has occurred. It will stay on until system or component passes the same test, for three consecutive trips, with no emissions related faults. If vehicle is experiencing a misfire malfunction which may cause damage to the Three-Way Catalytic Converter (TWC), MIL will flash once per second. This will continue until the vehicle is outside of speed and load conditions which could cause possible catalyst damage, and MIL will stop flashing and remain on steady.