Malfunction Indicator Lamp: Description and Operation

Instrument Panel:

The CHECK ENGINE light will come ON to notify the driver that a malfunction in the Emission Control System has occurred.
When the irregular signal returns to normal and the Control Unit judges that it has returned to normal, the light will go out. Also, when the ignition switch is turned OFF, the light goes out. Even if the ignition switch is turned ON again, the light will not come on until the irregularity is detected again.
When the ignition switch is turned on, the CHECK ENGINE light will light for 2.5 seconds to indicate that it is operating normally.
An irregular signal, from any of the following items, will cause the CHECK ENGINE light to come on:

^ MPI Control Unit
^ Oxygen Sensor
^ Air-Flow Sensor
^ Intake-Air Temperature Sensor
^ Throttle Position Sensor
^ Coolant Temperature Sensor
^ Crank Angle or
^ Top Dead Center Sensor
^ Barometric Pressure Sensor
^ Injector
^ Fuel Pump
^ EGR System (on California model vehicles).
^ Ignition Coil