Quick update,
@hahnmgh63 nailed it, got the car on lift and removed the ECS x-pipe to look for any cat pieces and found a big chunk caught down all way on exhaust valve. Photo attached
Now what’s my options ?
I saw JHM has some headers with/without cats, but I live so far away to send/wait for headers.
If I just gut them out ,is there a way to disable code without tune ?
Also is it possible to remove the headers without removing engine ?
You have to pull the engine to do the Headers. As a minimum you’d have to lower the whole assembly with the cradle. Owners would be surprised how bad their Cats are and how short the life. I’ve seen 3 sets with varying mileage from 26k to 99k and even the 26k set showed signs of wear/damage starting. JHM says they’ve never seen a good OEM RS5 Cat.
Not sure if a shop could pull the down pipes and gut the Cats from there so you wouldn’t have to pull the engine. If you have to have Cats, the JHM downstream Cats would be the better option for high flow and longevity (less heat and direct the pressure is higher, probably better quality too).
I doubt anyone makes a stock tune with a Cat delete file. I’m running JHM’s Stg2 w/Cat delete & SAI delete.
Appreciate you inputs Mark, will check local shops here if they can gut the cats with downpipes removed
not many shops here i would trust removing engine tbh
was also thinking of O2 spacers for downstream sensors to avoid getting a tune
any experience with those ?
I’ve heard hit & miss with O2 spacers. For the price they’ve got to be worth a try though. I think there’s someone else on the forum here that lives down in Dubai, and I think he did the JHM Stg2. I do remember him complaining about the lack of choices for auto repair. The way to inspect the conditon of the Cats is to use a video inspection camera you insert it through the upstream and downstream O2 sensor holes and inspect the surface of the Cats. Obviously your one Cat is pretty much gone. At least you got that big chunk out of there and the rest of that Cat at least will probably follow suit and blow down the exhaust. It would be good to inspect both sides. I have a pretty good Snapon inspection camera but I think nowadays you can get a pretty decent one that just attaches to your Iphone. I know a CEL is annoying but as long as your Cat is not clogging your exhaust then it should be safe. The rear O2’s are pretty much and emissions check system, measuring the efficiency and operation of the Cats. A gutted Cat, or one mostly blown out won’t hurt your car, but a clogged/fused together Cat can. So you’re probably doing good on the side with the chunked out one, better check the other one, if it’s Ok for now you can put off the repair until you find the shop you want.
Ordered O2 spacers with mini cat inside to test,
Just was thinking about fault ( rich to lean slow ) could it be also leaking injector ? Giving too much unexpected fuel ?
When I look at cat from downstream sensor whole I see no broken parts just the grove in the cat for sensor tip to be inside
So I’m thinking maybe it’s broken from down side, and wondering how that affects sensor readings as all air coming to sensor passing through cat material as it looks to me.
What you guys think ?
A too rich condition can definitely ruin a Cat by causing unburnt fuel to burn further in the Cat and overheating it. RS5’s are designed to run a little rich, performance oriented, but they can’t run too rich or they will not pass emissions. Is that Cat you looked at the one that you found the chunk out of in the Downpipe?
I was not sure initially which side is bank 2,
Then found on other forum some info that bank 2 is driver side, hopefully that’s correct
So I checked only driver side CAT and sensor
The broken piece was also in driver side exhaust tip all way stuck on valve, not in downpipe I have ECS x-pipe installed could it be from bank 1 and crossed sides from the x pipe ?
I could.only insert the endoscope camera from downstream sensor whole and can see cat ceramic all around
So guessing might be broken underneath sensor groove.
Need to remove downpipes both sides and insert camera there to check
Your right, with the X-pipe who knows which side it is from. Assuming you are LHD, bank 2 is on the Left, Bank 1 on the right, not sure how the Germans came up with that but it is the same for Porsche.
Try removing the upstream sensor and looking down from the top end. That is usually where the damage starts and expands from there.
Will try that hopefully can reach it 
But having code for Bank 2 is not enough Indication ?
Update !!!
Installed the spacer with mini cat inside, drove for a while and code came back still
is there any chance this code not related to broken Cat ?
couldn’t reach upstream sensor to see with endoscope to have a look, any tips ?
You can never be 100% sure with modern computerized controls, just have to follow the trouble tree. Dealer would most likey change the sensor first, and if that didn’t fix it they would recommend and engine pull to install a new Cat (and Demand your first born in payment for the price of the engine pull and the price of an OEM Cat).
Yes I agree,
Just don’t want to eliminate all possibilities before removing engine
This can’t be from leaking injector ?
A leaking injector could cause a rich condition on that bank which could cause deterioration/failure of your Catalytic converter. How many miles/Kilometers on the car now?
It has 116,000 now,
at 90,000 did carbon clean up with fresh seals for for everything
in case of leaking injector any other codes should come up ?
symptoms while driving ?
So i gave another kind of O2 spacer a try (basic one without any mini cat inside) and surprisingly it works
no cell for few days already.
just a temporary solution till i get time to take out engine
below photos for fancy O2 spacer with mini cat and basic one for reference
This one didn’t work
So at least for the moment no codes at all? If so that is a win.
Exactly, now no codes at all
I even monitored LTFT and STFT to compare what bank 2 doing compared to bank 1
looks ok to me, bank 2 could be like 1-2 % higher, that’s ok no ?
Br,
Ahmed
Congratulations. I’d keep an eye on the fuel trims, just in case one clogs. But I’d imagine from that big chunk you found down in the exhaust that the one side is fairly open. At least from the pic it looked like a pretty big piece. Although you now have the other side to worry about, if it fails, hopefully it will blow a big piece(s) down the exhaust too.
Thank you for all tips and help Mark,
yeah i got one of the OBD Bluetooth and have the app on my phone to monitor or even log if i need
hopefully other side will not clog 
and when breaks throw big chunk as bank 2 
The part that works (as in the photo), I found to be of make Faceuer:
Faceuerepya9nsx584458
Dimensions 8 x 6 x 4 cm; 90 grams
Congratulations on the fix and the good intuition.
