Malfunction Indicator Lamp: Description and Operation

The CHECK ENGINE lamp illuminates when the ignition key is turned to the ON position and stays lit for 3 seconds as a bulb test. The CHECK ENGINE lamp is also illuminated when the engine controller receives an erroneous signal from one of the following:

^ Battery voltage input
^ Charging system
^ Coolant temperature sensor
^ Emissions related systems (California only)
^ Manifold Absolute Pressure sensor (MAP)
^ Throttle Position Sensor (TPS)

When the lamp is lit, it indicates that the engine controller has gone into "Limp-in Mode" in an attempt to maintain operation. It signals that there is an immediate need for service and/or repairs. In "Limp-in Mode", the engine controller substitutes preset values for certain components.
The CHECK ENGINE lamp can also be used to display fault codes. To access any stored fault codes, turn the ignition key ON, OFF, ON, OFF, ON within a five second period.