2004 A4 B6 Avant 130k... the usual Bosch ABS system and predictably it has failed. Message centre flashing "BRAKES!" and ABS lamp plus flashing hand brake lamp, as would be expected from this unit when it goes down. However, when scanned with dealer software, and then again with VAG.com, there are NO fault codes whatever on the car!

On running a full on diagnostic with VAG.com, brake line pressures all register OK, ABS can be cycled (i.e everything works) when prompted by the diagnostic. Testing the brakes on a slippy carpark, no ABS function is present.

Just to say again, there are no error codes at all on the car, despite 2x diagnostics but clearly the ABS light is on and the system is inactive - a seemingly impossible situation? As far as the car is concerned all is well with the ABS system - but it's flagging a warning and the ABS is inactive. Got me stumped - any ideas out there? ...apart from chucking a new ABS module at it for £1000 "on the offchance that's it" – or does anyone know any good Audi breakers who pay top dollar?? :)