Audi ABS breaking system error
if the ABS fault light comes on as you turn on the ignition and control unit can't be accessed with a fault reader then the control unit itself is faulty and must be repaired or replaced. if can be accessed, should store a fault in the memory, most probably in a wire to wheel speed sender. if light comes on only after vehicle is in motion than fault will be a dirty or incorrectly adjusted speed sender.
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