tozoM8

The downpipe from the manifold to the cat usually just a pipe. I am working on an 02' and the o2 sensor is before the cat. I've looked up there is a cat looking thing. I don't have ETKA here in the shop. Thanks!

mpollan

YGM - Looks like one per side per ETKA

TwoTonic

I'm looking at Bentley on eBahn. From the exhaust manifold, the exhaust pipe does have a broader element mid-pipe, after the O2 sensor, then mates to the cat itself. Not clear if that is just insulation or if it's a pre-cat like some GM cars use.

I'll send you a PDF of the system on PM right now.

TwoTonic

Sent you PM with diagram

Sleeper8

Re: I need some help. It looks like the 02' A8 has 2 cats/side. Can anyone confirm it for me?

tozoM8

That down pipe is a pre-cat and it has the o2 sensor front of it. It goes down just like the other years and after the flange is the cat converter.
<img src="http://pictureposter.audiworld.com/80919/imag0020.jpg">
The after cat o2 sensor is right front of the cat not after like the older ones.
<img src="http://pictureposter.audiworld.com/80919/imag0021.jpg">

PaulW

So did the 00 cat work?

mpollan

as separate components. The right side has the pipe and TWC as one unit. Are you thinking the "bulge" upstream of the TWC is a pre-cat converter?

Tank1030ok

So far no engine light is on but I will find out next day or so.

tozoM8

Yes, there are two more on the 02'. The down pipe is a cat.