Malfunction Indicator Lamp (MIL), Significance

Malfunction Indicator Lamp, Significance

If the engine control module recognizes malfunctions which adversely affect exhaust emissions, the Malfunction Indicator Lamp -K83- (MIL) will turn on.







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.
- Permanently on when switching on the ignition: 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. [1][2]Reading Diagnostic Trouble Codes


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 exhaust gas warning lamp does not light-up with ignition switched on:
- Check combi-instrument and exhaust emissions warning lamp as follows:

If the MIL does not illuminate with ignition on:
- Check MIL lamp wiring / MIL lamp bulb using wiring diagram.

If OK:
- Start engine and run at idling speed:The 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. [1][2]Reading Diagnostic Trouble Codes
- Display readiness code. If DTC memory has been erased or Engine Control Module (ECM) was disconnected from permanent positive, readiness code must be reset.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes