Thanks for all the help!
(This is my first post.)
By searching the message boards I was able to solve all of my check engine problems without asking any questions.
I have a 2002 TT Coupe with no mods except GIAC flash. 133K miles.
I was getting multiple check engine lights and my thermostat had failed.
Problems solved:
1. Thermostat replaced. (What a chore.)
2. Coolant reservoir replaced.
3. Plugs replaced. Denso Iridium IK20.
4. Numerous vacuum leaks hunted down and solved.
As I solved each problem, it threw a new and different set of codes until I found the last vacuum leak. After that, it threw a few more codes while I think it was adjusting the fuel map to adapt to the new conditions.
I have a VCDS lite with a generic cable.
With just two 10 mile drives, I got full readiness, and now I can get my emissions certification in the morning. (Georgia.)
Ciao!



