Recently purchased a 2002 A6 3.0. The price was lower than most around, and this one was very clean and ran smooth, soI jumped on it. I've been very happy driving it, it has to be the most exiting car I've owned.

About 2 weeks after I had purchased it the CEL came on. Read codes P0491 & P0492. Seondary air system failure. I'm pretty good at reading vacuum/electrical diagrams so I figured I would take a crack at it before taking it to the local dealer. I've used alldatadiy in the past, I was quite happy to find they have pretty good diagrams for this model/engine.

Anyway after a little looking around I found a vacuum hose had fallen loose. It is located on the plate under the rear plastic engine snap oncover coming from the seconday air solenoid valve. The hose connects through the mounting plate and is a terrible design.. Because it is stright up and down it is almost guaranteed that vibration will pull it loose every once in a while.

Just thought I would post this to help folks with that code out in the future.

Also, anyone know if the CPO warranty covers emmissions related stuff, like the secondary air system????


2002 A6 3.0
All stock