Malfunction Indicator Lamp: Description and Operation

"Check Engine" Light:

This system incorporates self-diagnostic capability that is monitored via a dash mounted "Check Engine" light. When the system detects a fault in a monitored component and/or circuit, the light will come on and stay on (while the engine is running), alerting the driver to seek service. With intermittent problems, the light may come on and then go out, but a trouble code will be stored in ECM memory if correct parameters are met. The technician can then extract trouble codes from the ECM that will aid in the performance of efficient troubleshooting and repair. Faults detected in the following systems will cause the "Check Engine" light to come on:

Air flow sensor system
Coolant temperature sensor system
Vehicle speed sensor system
Oxygen sensor system
Knock sensor system
Fuel injection system
ECM micro computer