I just sold my 99 a4 so when I saw an a8 for $2000 I had to check it out. The car I'm considering is a 1999 4.2 quattro with tiptronic, its in good cosmetic shape, the cold start was rough but the car had been sitting for some time, after it ran for 5 minutes or so I turned it off let it sit for a minute and restarted it and it was much smoother, the check engine light is on, the car drives fine in manual mode, but when in automatic it has trouble shifting between 3rd and 4th. Is this the kind of thing that indicates catastrophic transmission failure on the horizon or is this just some sort of electrical gremlin that could be ignored if I don't mind not using the automatic mode? should i have the trouble codes checked or just forget this thing?

 

Could be an electrical problem, but knowing the D2 transmission layout i would say it needs a new tranny and the owner knows it. You can expect to pay 3-4 times what you paid for it to fix it. If thats worth it to you, then buy it. You can't find a better car that was made in 99.