2001 Allroad, 2.7T check engine light comes and goes, checked the code right bank is too rich. Anyone have this issue? I just had 90K service preformed at dealer.

 

If it's a fueling issue, chances are it's an oxygen sensor that's causing trouble. I believe the primary O2 sensors (the ones that determine fuel mixture) are bank-specific, so I'd replace the right bank primary O2 sensor and it'll probably cure your issue. If you feel industrious, swap that O2 with the primary on the left bank and see if you get a new code indicating that the rich condition has moved to the left side - that'll be conclusive proof.

As for buying a new O2 sensor, I read recently that www.PureMS.com has them for about $107 for the B5 cars (which likely will share the part with your AllRoad).