Malfunction Indicator Lamp: Description and Operation

Check Engine Light (malfunction Indicator Light):

A "Check Engine" Light will illuminate to notify the driver that an indication of a malfunction in the emission control system has occurred. Immediately after the ignition switch is turned on, the "Check Engine" light will light for 2.5 seconds to indicate that the light operates normally. An irregular signal from any of the following items will cause the "Check Engine" Light to come on:
ECU
Oxygen sensor
Air-flow sensor
Intake air temperature sensor
Throttle position sensor
Engine coolant temperature sensor
Crank angle sensor
Vehicle speed sensor
Top dead center sensor
Barometric pressure sensor
Injector
Fuel pump
EGR (California only)
When an irregular signal returns to normal the "Check Engine" light goes out. Also, when the ignition switch is turned off, the light goes out. Once the ignition switch is turned off, after the ignition switch is turned on again, the "Check Engine" light does not come on again until the irregularity is again detected.