Had same problem with my 99 Passat, no sensor faults, turned out to be a no comms link to ecu from abs pump modulator. If u can get hold of a reliable and experienced auto sparky in ur area, they can check this for u. Modulators arent available seperatly i dont think for ur car, beware of replacing the entire pump for two reasons : 1 : make sure numbers match EXACTLY as ur old unit 2: the obvious, they might be faulty also. My repair was done by a specialist whilst i was still able to drive the car,,,,result !! Cost was a fraction of a new one too and comes with a warranty......job done and £130 approx.

Hope this helps, no warning buzzers or blinking duo of lights....