Hi fellow Audi owners,

A6, 3.2, 2005
Codes: P0171, P0174, P2296
Symptoms: Rough start, poor acceleration and power loss, ESP & Check Engine Light

A week ago the ESP light came on while driving, then a mile or two later the check engine light also came on. Took the car to AutoZone for a scan because I don't have a VAG-COM. Their scanner is showing codes P0171, P0174 and P2296. I always first try the self help approach, and so I've been reading and studying these codes and remedies others have used to correct these codes. From what I've read as being common, these codes typically relate to a vacuum leak - causing Bank 1 and 2 to be lean. I tried listening as best as I could for the hissing sound of a leak with the car idling. I thought I pin-pointed it: vacuum check valve. I ordered the OEM replacement part and swapped the old for the new. The CEL and ESP light are still on, though. So I'm thinking this wasn't the leak, or there never really was a leak and it's, in fact, something else. Any suggestions whatsoever would be greatly appreciated.

Thanks in advance.