I recently bought a 2003 S4 and initially it was great fun, just a couple of faults. The airbag light would come on after 9 minutes and the air con wasn't working.
fixed the airbag light - a new module was needed as the old one would not code to the replacement instrument cluster. Gassed up the air con but it all leaked out again :-(. Seems like I have a leak so replaced all of the o rings at the condenser and pump but still won' t stay pressurised. Looks like a pump is needed at huge expense!
then noticed that the upper control arms were shot. Easy job I thought but the pinch bolt was well and truly seized. Even heating with oxy torch would not budge them. So I gave in and bought a pair of used uprights and put them on. Trouble is my old wheel bearings were also seized - 3 out of 4 bolts either side came out the other rounded. All put back together so took it to get it tracked - the track rod end is seized in the track arm. So now I have to replace both but of course the track rod will not come away from the rack. To cap it all on a test drive the traction control light keeps flashing and cuts the engine even at low speeds so looks like an abs sensor has been damaged during the swap.
Getting concerned that this is a problem car and 1 thing will just lead to another...