I need some input from you Audi techs...

The 0411 code points to the secondary air injection (egr valve) and the 0422 code points to a bad catalyst, bank 1. My question is, can a bad egr valve, or vac hose going to it, cause the 0422 code? Is the EGR normally suspect, or is more typically a vac hose?

Previously, I had replaced the valve cover gaskets, plugs and wires, and coil packs... so I have eliminated a bad spark discharge as a suspect hopefully.

Any input would be most appreciated!

98 A4 2.8 fwd

 

i don't think a bad EGR will foul a cat. your cat might not even be bad actually. get under the car and punch the cat a few times and see if you hear rattling from it. if not, it's your 02 sensor that's rly dirty. if you do hear rattling, your cat is bad and be prepared to pay some money. as for the egr valve, find it and see if you can clear it out by blowing into it or intake cleaner. do you hear a high pitched whining sound during a cold startup?

 

Agreed, a bad EGR will not foul a cat, and I don't think the cats are bad... I'm just trying to figure out what's throwing the code. Also, the O2 sensors and O2 sensor heaters check out OK. (at least by the emissions test) There is a high pitched whining sound at at start up, but I'm almost positive it is the a/c clutch acting up. When I turn the a/c off, the sound goes away. What else would produce that sound?

 

I was also getting the EGR code. The thing is that if you refuel incorrectly, your car will throw this code back at you. I seafoamed my car twice and then still had the code. I went over to autozone and had them delete it, it hasnt come back. I cant tell you anything about the cat though.