Malfunction Indicator Lamp (MIL) Significance

If a malfunction is recognized by the Engine Control Module (ECM) or the Transmission Control Module (TCM), this is indicated by the MIL coming on.

Malfunction Indicator Lamp (MIL)







NOTE:
When a recognized malfunction switches on the MIL, it will either blink or light continuously. In either case, DTC memory must be checked.
- If the MIL starts to blink, there is a malfunction that can lead to damage of the Three Way Catalytic Converter (TWC). In this case, driving should only continue using reduced power. The malfunction must be rectified as quickly as possible.
- If the MIL lights continuously, there is a malfunction that affects exhaust emissions. In this case, DTC memory must be checked, and the malfunction must be rectified as quickly as possible.
- Some malfunctions may occur without causing the MIL to come on When driveability or performance problems are reported, and there is no indication from the MIL, the operation of the MIL must be checked. In addition, DTC memory must be checked, as there may be malfunctions stored that do not switch the MIL on immediately.

Checking function
- Switch ignition on.
MIL must light UP.
- If MIL does not light when ignition is switched on, check wiring to MIL as follows.

Cause:
MIL is not triggered, or does not light, due to faulty wiring or open circuit.

Corrective action:
- Switch ignition off.
- Connect VAG 1598/22 test box
- Connect jumper wire to bridge test box sockets 2 and 17.
- Switch ignition on.
- MIL must light up.
If MIL does not light:
- Switch ignition off.
- Check bulb for MIL.
If bulb is OK:
- Check wiring for open circuit between MIL and Motronic ECM -J220- using applicable wiring diagram.
If wiring is OK:

Malfunction:
Motronic ECM -J220- is faulty; replace. Check and erase Diagnostic Trouble Code (DTC) memory and generate new readiness code.Readiness Code, Generating

If MIL lights up when ignition is switched on, continue checking as follows:
- Start engine and let run at idle.

MIL must go out after a few seconds.

If MIL does not go out:
- Check Diagnostic Trouble Code (DTC) memory.

If there are no malfunctions stored in DTC memory:

Cause:
MIL is triggered continuously due to short circuit to Ground.

Corrective action:
- Switch ignition off.
- Connect VAG 1598/22 test box.
- Check resistance between test box socket 17 and vehicle Ground, specified value: Infinity Ohms (no continuity)
If the specified value is not obtained:
- Check for short circuit to Ground in wiring from Motronic Engine Control Module (ECM) -J220- to MIL.
- Trace malfunction using applicable wiring diagram and repair as necessary.
If there is no continuity, and no short circuit to Ground:

Malfunction:
Motronic ECM -J220- is faulty; replace. Check and erase Diagnostic Trouble Code (DTC) memory and generate new readiness code.Readiness Code, Generating