Two problems related to manifold/header/muffler/tail pipe have been reported for the 2008 Audi Q7. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Audi Q7 based on all problems reported for the 2008 Q7.
The upper plastic intake runner flaps in the intake manifold broke causing the flaps and plastic debris to be pulled into the intake ports of the cylinder head resulting in intake valve and injector damage. This caused the engine to stop running.
Intake manifold flap on passenger not opening fully causing the check engine light to turn on. I checked the web and I there are a lot of complaints about the same problem. I've had BMW, mercedez, Toyota's and a lot more, none of those vehicle gave me problem. Audi is taking care of other models with 2. 0 tfsi engine, they extended the emmission warranty to 10 yrs or 100k. Audi should take care of this issue aswell.