Shop found codes P0431 & P1131 for bank 2 O2 sensor circuits and recommended replacing bank 2 cat converter and both sensors for a mere $2300. Dang California doesn't allow sale of aftermarket cat converters for the A6. I think I'll go to NV and buy a universal fit or have a buddy in another state mail it to me. Anyone have any experience with this issue and cost?

 

Hi NICKV,

If the diagnostics codes you have are correct, it sounds as if the P0431 is indicating a bad Cat Converter. The quote you got sounds extremely high!! I would shop around for a more reasonable quote. The Cats are expensive to replace, but for the price you were quoted you could replace the entire exhaust system.

P.S. In the future, its easier to help with a diagnosis if you include the year, model, engine, etc. for your car.

 

Call Force Five in Concord NH for Audi Cats at a good price...

 

If cost is a big factor get an aftermarket cat. Something by walker maybe

 

Yeah if this is a 3.0L the dealer will charge $1,000 a piece for the stock Eberspacher cat converters. You can find after market sets for less than $400 per cat, Walker, Benchmark makes a good aftermarket cat/downpipe for around $350 per cat.

P.S. I hope you don't live in california because most aftermarket cats are illegal here, but smog shops can't tell the difference/don't care. If you can get a company to ship them to you then get those. Here is an example of my point. http://www.familycar.com/store/?Ntt=...erter&oes=true

 

I don't see any reason to pay 1000$ a cat... a turbo maybe, but for a cat? I'm glad I don't live in cali. I don't know if I could ever realize my automotive fantasies with all their regulations.

 

Sadly, I do live in Cal. Someone suggested a magniflow universal fit which runs about $68. But looking at the cat on the car there appears to only be about an inch between the cat and a "pre-cat" (what is that metal mesh section about 6 inches long before the cat? I'm guessing I'd at least need the down pipe? Looks like there is a slip on for the rear pipe to muffler after the cat. Does that seem right? I've got friends in other states where I can pick up or have them ship to me. I might check with a muffler guy to see if he has room to cut on between cat and pre-cat thingy.

2000 A6 2.7T Quattro

 

There is no pre cat, the cat is built into the down pipe. The "mesh" thing is the flex pipe which is part of the downpipe. Towards the center of the car is the resonator, and then the muffler at the back. You are thinking the resonator is the cat converter which isn't the case. It would be super difficult/expensive to use a universal cat on an A6. You would need to remove the entire downpipe then cut out the original cat and some of the original pipe. Custom mandrel bend some pipe and weld in the universals for it to work.
On top of that you live in california so if the smog technician sees the welding points on the downpipe (hard to see though) he would automatically fail you on the visual inspection. I would see if you could score an aftermarket downpipe/cat set up that at least looks stock, if not, you have to bite the dealer's silver bullet.

 

I'm icing a knee right now so I can't take a look but I'm pretty sure I was looking at both cat converters right after the bend in the down pipe. If I recall both pipes come together toward the middle (can't remember resonator) then mufflers. Good advice though. I can still buy a AM downpipe/cat set up for a lot less than OEM at shop. Probably should replace both down pipes just to be on safe side. Good info...helpful...thanks a lot!

 

My wife's A6 has the 2.8, so I don't know how different the exhaust system is from a 2.7T, but on hers, using universal cats was by far the least expensive fix, and it wasn't all that difficult. I disconnected the coupling behind the cat on each side, and once you cut the cats off, you can pull what's left of the down pipe down at the flex coupling enough to weld the new cat on without even taking the pipe loose from the manifold. The universal cats I got are round, so you lose about an inch of ground clearance, but for $60 each, its a worthwhile tradeoff.