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Catalytic Converter hole


2006 B7 S4 CAB. Noticed engine light on way back from Heathrow the other day. Got it checked today and although it says the O2 sensor, when it was up on the ramp soon spotted that the offside cat at the flexible joint between cat and manifold had developed a leak and was blowing. He says its highly likely this caused the engine light and not the sensor.

Both of these flexible joints (off and near) look pretty old, so I asked my mechanic to price up replacing - and then nearly fell off my chair.

Genuine audi parts even with his discount came in at 747 + VAT EACH! And thats without fitting. Having just moved into a new house this was devastating - looking at best part of 2k to replace them both.

Question I have is:-

I suspect aftermarket Cats would be way way cheaper - has anyone run them or have advice? Or would you only go genuine VAG, I plan to keep the car long term so if I have to I will save the cash and have it done (its only a small chuff at the moment but no doubt will get louder)

Thanks for help!


An exhaust fabricator may well be able to weld new flexi joints onto your existing cats.

Thanks Graham, I'll try my local exhaust specialist and see what they say!

Will post an update when I get the chance.

Fingers crossed for you

Hey whereabouts are you?
I just did this on mine. It was a bitch of a job as the downpipes had to come off to fully weld them up but it cost me less than 20 for a pair of flexis off eBay. I also gutted the precats at the same time.


Exhaust people finally got round to doing it. As you suggested they cut the flexi part out and replaced and welded, only driven it back from the garage so far so will let you all know. But I think the neighbours will be happier!

Cost 400 total - they had it the whole day, said getting it off was a real pain.

Only did one side for now, the other will go in time I suspect but still WAY cheaper than replacing the whole piece including CATS. Forum Index -> Audi S4 & RS 4 (B6 & B7) quattro
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