Solving your issue. Locating it is easy. Look for the Serpentine belt and it is the item on the belt with a pulley and fins as in the videos and images on the parts site. You can't miss it. Why do you think you need an alternator?
JustAnswerhttps://www.justanswer.com > Audi Repair Dec 21, 2008 - When you reinstall the alternator it is very difficult to get the ears over the mount and line up the holes. The solution: On the alternator the ... 1 answer · Top answer: Hello, Thank You for choosing "Just Answer" for your questions concerning your Audi. Yes, ...
In my A4, it's on the side of the dashboard (driver's side), where the dash mates to the door when the door is closed. Check there and see if you can pop off the end panel on the dash.
You need to scan the codes to find what the fault is. If you have access to a VagCom you can get the codes yourself. Otherwise take it to AutoZone (they sometimes will check the codes for free), the dealership, or a smog test station and get the codes checked.