ABS Repair Information

ABS Repair Information


The anti-lock brake system is generally maintenance-free.

Testing, assembly, and repair work may only be performed by qualified personnel.

By not observing the points described in the repair information, the system can be damaged and vehicle safety could be compromised.

• Before performing repair work on the anti-lock brake system, determine the cause of the malfunction using On-Board Diagnostics (OBD).

• If you install a new hydraulic control unit, you must check its coding using the Vehicle Diagnosis, Testing and Information System (VAS 505x).

• Switch ignition off before installation work. On vehicles with coded radio unit, determine code and disconnect battery ground strap.

• When working with brake fluid, observe relevant safety precautions and notes. Refer to => [ Brake Fluid ] Description and Operation.

• If any work requires opening the hydraulic system, the first bleed the brake system using Bleeding with Brake Filler/Bleeder Unit (V.A.G 1869/) or Brake charger/bleeder unit (VAS 5234). Refer to => [ Brake System, Bleeding ] Brake System, Bleeding. Perform a high and low pressure test on the brake system. Refer to => [ Pressure Leak Test ] Pressure Leak Test.

• During final road test, ensure that an ABS-controlled braking is performed at least one time (pulsing must be felt in brake pedal).

• Absolute cleanliness is required when working on the anti-lock brake system, it is not permitted to use any products which contain mineral oil, such as oils, greases etc.

• Thoroughly clean all unions and the adjacent areas before loosening. Do not use aggressive cleaning agents such as brake cleaner, fuel, thinners or similar chemicals.

• Place parts that have been removed on a clean surface and cover.

• Carefully cover over opened components or seal, if repairs are not carried out immediately. (Sealing plugs, use repair kit 1 H0 698 311 A)

• Only use lint-free cloths.

• Only unpack replacement parts immediately prior to installation.

• Only use parts in their original packaging.

• Do not work with compressed air and do not move vehicle while the system is open.

• Make sure that no brake fluid enters plug connectors.