Malfunction Indicator Lamp: Description and Operation

Check Engine Light (malfunction Indicator Light):

A malfunction indicator 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 light will illuminate for 2.5 seconds to indicate that the light operates normally. An irregular signal from any of the following items will cause the light to come on:
- ECU
- Oxygen sensor
- Air-flow sensor
- Intake air temperature sensor
- Throttle position sensor
- Engine coolant temperature sensor
- Crank angle sensor
- Top dead center sensor
- Barometric pressure sensor
- Injector
- Fuel pump
- EGR (California only)
When an irregular signal returns to normal the 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 light does not come on again until the irregularity is again detected.