posted on here a month or so ago because the esp light was intermittently coming on for no apprent reason, it would go out if the car was re started but only for 10 mins-ish. In the end i took ot to audi and had a diagnotics run but it came back with nothing. They suggested getting the wheels re-aligned which i did but it made no difference. Had the wheels speed sensors changed and brake light switch changed but still no joy.
Then whilst waiting at the gates to leave work last week the guy waiting behind me came up and knocked my window and said one of my brake lights was flickering. When i got home i took the light cluster out and found the circuit inside had rusted, gave it a clean up and soldered a small piece of fuse wire across the gap where it had corroded (just temporary). To my amazement the esp problem hasnt happened since!!
Don't understand how but it has solved the problem.