Does anyone know why the ABS pump on a '99 A3 would occasionally activate for no reason? its obviously a fault or getting a signal from somewhere. just wondering if its more likely to be something simple that can be fixed at home?

Normally it is either a cracked ABS ring or a faulty sensor. The sensor is an easy fix, the ring less so.

Does it activate even when you aren't braking?

You don't need to shove the pedal as hard as you did in the MAC1 Darren

I dont drive the car much so still trying to determine what is happening. Seems to be only when braking, generally at slow speed. Intermittent.

Ive recently put new discs on the back, rings were a bit crudded up - now cleaned with brake cleaner. No sign of cracks.
Garage has just done the fronts so not sure what condition the ABS rings are.

Ive noticed the yellow ABS warning light on the dash occasionally. Brake pedal feel is a little softer than id like, just had to have a corroded pipe replaced so could be a little air in the system still.

i might try cleaning the rings and connections at the hubs. Is there a sensor on the pedal too or is that only for brake lights?