Malfunction Indicator Lamp: Description and Operation

The Malfunction Indicator Lamp (MIL) is on the instrument panel. The MIL has the following functions:
^ The MIL informs the driver that a fault that affects the emission levels of the vehicle has occurred. The owner should take the vehicle in for service as soon as possible.
^ As a bulb and system check, the Malfunction Indicator Lamp (MIL) comes ON with the key ON and the engine not running. When the engine is started, the MIL turns OFF if no DTCs are set.

When the MIL remains ON while the engine is running, or when a malfunction is suspected due to a driveability or emissions problem, perform an On-Board Diagnostic (OBD) System Check. The procedures for these checks are given in engine controls. These checks expose faults which the technician may not detect if other diagnostics are performed first.