Glad I read this thread, my warning light has come on for the parking brake, last week it didn't cycle properly and now the error - although it still seems to work OK. I know the rear pads are 80% worn but I don't know if this affects it or not?
Will run it into Audi next week but I bet they say "new caliper @££££££ please" so if it is just a sticky piston I will look at doing the seal change. Otherwise maybe it just needs a good clean up? Haven't put 50k on it yet but I guess mileage has nothing to do with number of brake activations...
Any suggestions welcome...