Just got my Mum a 3.0 Quattro A4 Cab 04 plate. Since having it the ESP light has been coming on & off, she had two day & it didn't come on once but other times after a few miles. When we got it the only thing that I noticed when we got it back was that the front had the spare fitted & it was a conti sport contact 2 & all the other three are sport contact 3. Also the spare had more tread than the rest so I thought it might have caused a sensor to trigger or something like that. Anyway I told her to go get a part worn sport contact 3 with the same tread as the others as a Quattro should have the same tyres all round, she has now done that but the ESP light still comes on. Any ideas?