Malfunction Indicator Lamp: Description and Operation

Check Engine (Malfunction Indicator) Light:

The Malfunction Indicator (Check Engine) light is mounted in the dash and reads CHECK ENGINE or SERVICE SOON. The CHECK ENGINE light will ILLUMINATE when the engine is operating in Limited Operating Strategy (LOS). The light will stay ON as long as there is a fault in the system. The CHECK ENGINE light can also be used to retrieve fault codes from the Electronic Engine Control (EEC) system when the self test mode is entered.