Malfunction Indicator Lamp (MIL)

NOTE: If the Engine Control Module recognizes malfunctions which adversely affect exhaust emissions, the Malfunction indicator Lamp (MIL) will switch ON.







Location of MIL lamp

1 - Malfunction Indicator Lamp (MIL)
2 - Glow period warning lamp


NOTES: The glow period warning lamp has a dual function:
- Flashing: malfunctions are recognized which affect the handling. Stored malfunctions can be displayed via the VAG 1551/1552 Scan Tool
- Permanently ON when switching ON ignition: Normal function when starting a cold Diesel engine.
- Malfunction Indicator Lamp is switched ON when malfunctions are recognized which adversely affect exhaust emission values. In this case check DTC memory. Checking DTC Memory (Function 02)


Functional Check:
- Switch ON ignition:
- The MIL lamp must remain lit until engine has started. (The glow period warning lamp can also light up during preglow period when engine is cold).
If MIL lamp does not light-up with ignition switched ON

- Check wiring to MIL lamp as follows:

Cause:
MIL lamp is not activated or does not light-up due to open circuit.

Remedy:
- Switch OFF ignition.
- Connect Test Box VAG 1598/18.
- Bridge Test Box sockets 1 and 60.
- Switch ON ignition.
MIL lamp must light-up.
If the MIL lamp does not light-up:
- Switch OFF ignition.
- Check bulb in MIL lamp.
If bulb OK
- Locate and eliminate short or open circuit between Engine Control Module J248 and MIL lamp using wiring diagram.

If MIL lamp wiring OK

Cause of malfunction
Control Module J248 faulty, replace. Erase DTC memory and create readiness code.

If the MIL lamp lights-up with ignition switched ON, continue check as follows:
- Start engine and let idle
- MIL lamp must go out after a few seconds.

If the MIL lamp does not go out:
- Check DTC memory. Checking DTC Memory (Function 02)

If no malfunction stored

Cause:
MIL amp permanently activated by short to Ground.

Remedy:
- Switch OFF ignition.
- Connect Test Box VAG 1598/18.
- Check resistance between Test Box socket 60 and vehicle Ground:
Specification: Infinity Ohms
If specification not obtained:
Short to Ground in activation wire between Engine Control Module J248 and MIL lamp.
- Locate and eliminate malfunction using wiring diagram.

If specification Infinity Ohms obtained and no short to Ground detected:

Malfunction cause
Engine Control Module J248 faulty, replace. Erase DTC memory and create readiness code.