Malfunction of the ABS system (Audi A4 B5)

When the ignition is switched on, the ABS indicator light on the instrument panel flashes. It should go out when the engine starts, or at the latest when the speed exceeds 6 km/h. If the on-board voltage drops below 10 V, the indicator light also lights up. It can also light up if one of the wheels slips for more than 20 seconds. Then switch off the ignition again and restart the engine.

If the light is constantly on, the ABS is not ready for use. An Audi or Bosch workshop should determine the cause. As an amateur, you can at least check the plug connectors of the control unit, speed sensors or hydraulic module. In addition, it is recommended to disconnect the speed sensors and clean their front side.

Tip: Even if the ABS indicator light is constantly on, i.e. ABS is not working, you should drive the car with the electronic brake force distribution system not working. The rear brakes may lock relatively early. Particular caution is required on turns, where the Audi with locked rear brakes may skid. Drive carefully and find an Audi workshop.