I had a set of cats go after approximately 12-15k miles. So it maybe a possibility, especially if the MTM is running a little rich. Another thing to check is the EGR valve.

 

how much was your replacement on the cats...

i just have a hard time seeing that is the case..i mean i guess it does make sense.. jsut dont see what would lead to the cause of the cat failure.. i havent had issues with it till this.. and they wont just give at 20-25k without some other problem.

haha no car is invincible.. esp a b5 s4. But its been strong thus far.. well its still strong..just a little shaky ...literally... at idle at times. i did hit boost of a little over 20 yesterday..not sure if thats a good or bad thing..

 

I only paid $200 or so for both cats, however I have LaBree DPs so the cats are slightly different.

If is it a little more rough at idle check the misfires (you can watch when the engine is idling with the VAG-COM) if one cylinder seems to have a problems try a little trouble shooting, i.e. swap coil packs with the cylinder next to it and etc. I also run a little fuel injector cleaner through mine occassionally which tends to help with the misfires and rough idles.

Do a search on Audiworld S4 forum with the code and see what comes up.

 

How would you check the egr valve?

 

I'd check on AW for how to check the EGR valve....thats something I don't have much information on.

Might be a good idea to pressure test you car too....shaky at idle and that recent high boost spike may be a boost leak. Maybe not, but its not hard to check.

Sorry I couldn't have been more of a help with the EGR.

 

haha yeah.. wasnt too knowledgable on that.

Im talking to a buddy to do a pressure test.. i may head to mpls to do it this weekend. The initial thought before the scan was a vac leak.. so might as well.

 

Good luck....and let me know what you turn up.