On Board Diagnostic (OBD), Specific Functions

The OBD function of the ESP system can recognize malfunctions and store a total of 41 different Diagnostic Trouble Codes (DTCs).

Note: If a malfunction is recognized by OBD, the system concerned is switched off automatically for the duration of the current driving cycle. This is indicated by the relevant warning light in the instrument cluster,Refer to "Indicator lamp functions, overview" for more information.

CAUTION: If the OBD has recognized a malfunction then the brake system is only partially functional. Because the brake pressure at the rear wheels is no longer regulated via Electronic Brake Distribution (EBD), the rear wheels can lock even during light braking. This can cause the rear lid to open and therefore lead to an accident.

Note: The above does not apply to the DTC "01119 gear recognition signal" DTC table. If this DTC is recognized, no warning light goes on. This malfunction affects the front and reverse gear recognition function. The ABS control module -J104- can determine the gear using plausibility criteria.

If VAS5051 tester or VAG1551 scan tool was connected and is communicating with the ABS control module -J104- no regulation is possible. The ABS warning light -K47-, traction control indicator light -K86- and the red brake warning symbol are lit.

Each time the ignition is switched on, the system conducts a self-test. The yellow ABS warning light -K47- and the traction control indicator light -K86- come on to indicate that this self-test is being conducted. The lights go out after about 3 seconds. The self-test continues after the vehicle starts moving, as certain malfunctions cannot be recognized until the vehicle is moving.

The switching of relays, the clicking of valves, the start-up noise of the ABS return flow pump (at the ABS, may recognize the self-test hydraulic unit) and one pressurizer pump, and by a slight vibration at the brake pedal (usually at about 6 km/h).

These system-related effects are part of the self-test program, and this should be explained to the customer in the event of complaints.

On Board Diagnostic (OBD), technical data

Diagnostic Trouble Code (DTC) memory
^ Permanent memory; the contents are retained even if the power supply is switched off.

Data output
^ Rapid data transfer (operating mode 1).
^ The ABS warning light -K47-, the red brake warning symbol, and the traction control indicator light -K86- in the instrument cluster are lit, when a malfunction is detected and the relevant system is switched off.








On Board Diagnostic (OBD)
- Use VAS5051 tester or VAG1551 scan tool for On Board Diagnostic.