Alright, about two weeks ago my CEL came on and since then everytime I get gas whether it $20 worth or a full tank my car has trouble starting right after filling up. Strange. So, I went and got my codes pulled at Auto Zone today...This is what I got.

P0171
P0442
P0455
P0456

Any ideas?? I drive a 2007 Audi A4 2.0T with about 70,000 miles on it.

 

Most likely the N80 valve (purge valve). Sits on the top driver side of the engine back towards the firewall. Cost about $20 to $30 for the part (plus new hose clamps) and takes just a few minutes to change.

Here is the part: http://www.ecstuning.com/Audi-B7_A4-...urge/ES281033/

I changed mine about two months ago (exact same issue you explain). I had to give the dealer the mfg part number as they could not locate a purge valve or N80 valve.

 

Thank you!! I'm gonna try to get one from the dealer today.