Malfunction Indicator Lamp (Service Engine Soon)

Service Engine Soon/Malfunction Indicator Lamp:

SERVICE ENGINE SOON / MALFUNCTION INDICATOR LAMP
As a functional test, the Malfunction Indicator Lamp (MIL) illuminates at key-on before engine cranking. Whenever the Powertrain Control Module (PCM) sets a diagnostic trouble code that effects vehicle emissions, it illuminates the MIL. The PCM illuminates the MIL only for diagnostic trouble codes that effect vehicle emissions. The MIL remains on until the diagnostic trouble code is erased. The MIL either flashes or illuminates continuously when the PCM detects active engine misfire.

During active misfire, the PCM records the current engine operating conditions. The engine operating conditions are recorded by the PCM.

Items Indicated By The Service Engine Soon/Malfunction Indicator Lamp (Part 1):

Items Indicated By The Service Engine Soon/Malfunction Indicator Lamp (Part 2):

NOTE: Following a detected malfunction of the Powertrain Control Module (PCM), the service engine soon lamp lights up the next time the engine is turned on if the malfunction is still detected. However, for items marked with an asterisk (*) in the table above, the service engine soon lamp goes on the first time a malfunction is detected.

Once the service engine soon lamp is lit, any one of the following conditions will turn it off.
- When the PCM has found no malfunction after monitoring the power train three times (One time is from engine start to engine stop).
- A misfire or fuel abnormality when engine speed, coolant temperature, etc. are similar to those prevailing when the malfunction was first recorded, and the PCM has detected no malfunction.

CAUTION: If the service engine soon lamp is turned on by a malfunction of the PCM, the scan tool cannot communicate with the PCM, and the diagnostic trouble code cannot be read.