Malfunction Indicator Light

The Malfunction Indicator Light (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or an ENGINE symbol icon. As a bulb and system check, the MIL (MIL will illuminate when ignition switch is turned to ON position and engine is not running). When engine is started, MIL should go out. If MIL does not go out, a malfunction has been detected in the computerized engine control system or MIL circuit is faulty. To access codes, see SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.

The MIL indicates that an emissions related fault has occurred and vehicle service is required. The following is a list of the modes of operation for the MIL:

• The MIL illuminates when the ignition switch is turned to RUN position, with the engine OFF. This is a bulb test to ensure the MIL is able to illuminate.
• The MIL turns OFF after the engine is started if a diagnostic fault is not present.
• The MIL remains illuminated after the engine is started if the Powertrain Control Module (PCM) detects a fault. A Diagnostic Trouble Code (DTC) is stored any time the PCM illuminates the MIL due to an emissions related fault. The MIL turns OFF after three consecutive ignition cycles in which a Test Passed has been reported for the diagnostic test that originally caused the MIL to illuminate.
• The MIL flashes if the PCM detects a misfire condition which could damage the catalytic converter.
• When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition switch is in the RUN position.
• When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.