Malfunction Indicator Lamp (MIL), Significance

Malfunction Indicator Lamp, Significance


NOTE: If the engine control module recognizes malfunctions which adversely affect exhaust emissions, the Malfunction Indicator Lamp -K83- (MIL) will turn on. In vehicles from MY 2000, this is done by a signal sent by the ECM via the instrument cluster.

Location Of MIL Lamp:

1 - MIL Lamp
2 - Glow plug indicator lamp

NOTE: The glow plug indicator lamp has a dual function:

- Blinking: malfunctions affecting handling are recognized. Stored malfunctions can be displayed via Scan Tool VAG 1551/1552. MIL must illuminate when ignition is turned on: Normal function when starting a cold Diesel engine.
- Malfunction Indicator Lamp is switched on when malfunctions are recognized which adversely affect exhaust emissions. If this happens, check DTC memory. If Malfunction Indicator Lamp (MIL) lamp does not light up, but there is an engine running problem, or a customer complaint, check DTC memory, since DTC malfunctions which do not switch the MIL lamp on immediately can also be stored. Reading Diagnostic Trouble Codes

Malfunction Indicator Lamp, Checking (Through MY 1999)

Special tools and equipment
- Test box VAG 1598/22
- Multimeter VAG 1526/VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test conditions






- Fuses No.29 and 32 OK.
- Battery voltage 11.5 V minimum.

Functional check:
- Turn on ignition:

Malfunction Indicator Lamp (MIL) must illuminate until engine has started. (Glow plug indicator lamp also illuminates during glow period when engine is cold)

If the MIL does not illuminate with ignition on:
- Check wiring from the ECM to MIL.






If MIL -K83- lights-up with ignition on, continue as follows:
- Start engine and let idle
- MIL lamp must go out after a few seconds

If MIL lamp does not go out:
- Check Diagnostic Trouble Code (DTC) memory, if necessary, repair any malfunctions and erase DTC memory, Reading Diagnostic Trouble Codes

If no DTC is stored:






- Display readiness code. If DTC memory has been erased or Engine Control Module (ECM) was disconnected from permanent positive, reset the readiness code.