Elkhart Lake A6

I have a 1996 A6 Quattro...About a month ago I was turning into a tight parking spot and the motor quit. The check engine light came on but the car restarted and has been running fine since. I brought it in for its emission test yesterday which it failed. The code indicated was P1504 which is an "intake air system bypass leak detected". When I use the climate controls to view trouble codes, none are indicated. Do I need to have the check engine light reset at this point or should it have cleared itself? I presume if so, a Vag-Com or similar device is needed. Any assistance will be very much appreciated!

squidix9

Obviously the climate control method isn't telling you what the diagnostic computer is. Vag-Com can reset the code, butt he question is will it come back or not? If it is a hrad failure, it likely will.

I'd take a good look at you vacuum lines and fittings. On that motor there are enough to drive you crazy. The ISV is at the passenger rear of the manifold. Start there and work towards the throttle body. On my 30V I bought a long length of vacuum line and just started with one fitting and went about replacing them all. Solved a lot of little issues.

I bet you'll find some cracked/dry rotted/brittle lines and or fittings that should be replaced.