Malfunction Indicator Lamp (MIL)

Malfunction Indicator Lamp (MIL), significance

If malfunctions are recognized by the Engine Control Module (ECM), they will be communicated to the instrument cluster through the CAN-Bus and indicated by switching on the Malfunction Indicator Lamp (MIL).

Location of Malfunction Indicator Lamp (MIL)







NOTE:
The Malfunction Indicator Lamp (MIL) can be switched on in the flashing or permanently on mode. The Diagnostic Trouble Code (DTC) memory must be checked in every case. [1][2][3]Automatic Test Sequence

- Flashing: there is a malfunction which can cause damage to catalyst if driven in this condition. In this case the vehicle must not be driven using full performance!
- Permanently on: there is a malfunction which will increase exhaust emissions. Check Engine and/or Transmission Control Modules.
- If the MIL Lamp does not light up, even though there is an engine running problem or a customer complaint, the DTC memory must be checked, because malfunctions which do NOT switch the MIL Lamp ON immediately can also be stored.


Functional check
- Switch ON ignition
- Malfunction Indicator Lamp (MIL) must light up.

If the Malfunction Indicator Lamp (MIL) does not light up with ignition switched on:

- Check instrument cluster and MIL lamp wiring / MIL lamp bulb as follows:

If the MIL lights-up with ignition switched on, continue check as follows:
- Start engine and run at idle speed:

MIL must go out after a few seconds.

If the MIL does not go out:

- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory, Diagnostic Trouble Code (DTC) memory, checking and erasing. Reading Diagnostic Trouble Codes
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes