Looking at this article it looks like my ABS problem is a common failure on B5's. http://www.audiworld.com/tech/elec116.shtml Mine has displayed exactly the symptons described slowly getting worse until now when the ABS light is on all the time. The irony is that it looks like the failure is in the ABS ECU part of the controller which does nothing to control the ABS it just talks to the Main ECU to enable the warning lights on the DIS. Nice one Audi, another piece of unnecessary electronics! Looks like I need to remove mine to find the part number as prices seem to range from £40-500 on ebay.