This bulletin applies to all Volkswagen vehicles equipped with TDI diesel engines. Prior to replacing the glow plug relay (038 911 253), perform the following test:
1. Disconnect the coolant temperature sensor.
2. Turn the ignition to the on position.
3. Wait 20 seconds for the glow plug light to turn off.
4. Using the VAG 1551, read the fault code. If DTC 00522 appears, the glow plug relay is OK. If DTC 00522 and DTC 01050 appear together, the glow plug relay is defective and must be replaced.