FSI NOx Cat Replacement

wilco184

wilco184

Member of the year 2015
Hi,

My brother's FSI has a rattle that is most prominent when decelerating. After some investigation, we've traced the rattle to the second cat (the NOx one underneath the car). It seems that it's loose/broken inside and hence, rattles. It's also had a DTC stored with the description of 'catalyst below efficiency' or words to that effect, I can't remember the exact wording. The car drives fine and returns great economy.

As such, can anyone suggest a place to purchase a suitable replacement please? Is an aftermarket part liable to cause issues? Does it make financial sense to fit a used NOx cat from a breaker or similar? The fault isn't causing an immediate problem, but it's not right.

I would appreciate any suggestions.

Thanks,

Matt.
 
I have not seen any aftermarket ones and when new they are expensive, so a used one is probably ok especially if it is from a breaker.

Steve B
 
The businesses that supply stainless exhaust systems offer cats. A2s are reaching the sort of age where cat replacement is not unexpected. I'm not sure I'd want to be taking a chance with a used cat because of the risk of early failure.
 
Hi, there are a number of new aftermarket rear FSI cats for sale on ebay & motor factors, for £96-£150. Most are BM 91472H or Klarius 311984. I bought a BM one from Amazon a couple of years ago; it looked okay, but I sold it on as I only bought it as a spare. One thing to bear in mind is the original Audi section of exhaust is in one piece, from the NOX cat through to rear silencer. If you replace cat with NOX sensor you have to buy a joining piece as well & cut the existing exhaust to remove old cat.
 
Hi Matt

I'm pretty sure I've got a nox sensor and controller there that's known to be fault free. Let me know if that's any good to you and I'll dig it out.
 
Hi,

Thanks for your replies.

That's good to know about the aftermarket parts. My concern with the BM and Klarius cats is that neither contain the Barium Oxide required for NoX storage. I'm worried that if NoX storage is either reduced or stopped, then the car may no longer drop into stratified mode because the NoX content in the exhaust gas will never be temporarily stored.

As such (this is definitely a long shot), could I please ask if anyone has fitted an aftermarket cat and either suffered worse fuel economy or checked to see if stratified mode still operates?

Thanks for the help,

Matt.
 
I got Mabel booked into day for a full stainless steel exhaust and they said the price includes new cats (I did send them a. Picture of the fsi system that I found on here) Not having it done until I'm near where they are for ADI in October, but I'm looking forward to seeing how she is after.
(Il was the place you used, Steve - thank you for their details)
 
Thanks for the help, all.

I've sent them an email. It'd be interesting to know as well to ask anyone with an FSI and aftermarket exhaust or second cat if their fuel economy has dropped, or if anyone has checked to see if the lean mode still operates?

Teresa - look forward to hearing about the new exhaust. :)

Regards,

Matt.
 
BM Catalysts have been speedy in getting back to me, their customer service seems good.

Essentially, they could not reveal which materials the replacement cat is made from (including if it contained Barium Oxide or not), and that aftermarket parts are not required to meet quite as stringent tests as OEM (though that's not to say that lean mode wouldn't work). They did say though that since released in 2010, they have had no complaints about the part.

Regards,

Matt.
 
Teresa said:
I got Mabel booked into day for a full stainless steel exhaust and they said the price includes new cats (I did send them a. Picture of the fsi system that I found on here) Not having it done until I'm near where they are for ADI in October, but I'm looking forward to seeing how she is after.
(Il was the place you used, Steve - thank you for their details)
Click to expand...

Teresa, I hope you've made clear that you'll need specialist catalytic converters that retain NOx, rather than the standard model that was fine for my 1.4. I'm sure that they'll check your existing cats before they start work, they certainly did with mine.

If your existing cats aren't working I would expect you to have the Emission Control System and EPC lights on all the time. Do you have any means to reset them while you're down there?

At the very least I'd encourage you to hang on to the discarded cats until you know that the replacements are in full working order.

Obviously I hope all goes well for you (as it certainly did for me). I'll be quite nervous until we hear your result!
 
I note having looked at Infinity's website that they offer club discount deals with some requirements - would this be something A2oc would be interested in looking at given the number of cars that are going to start needing exhausts doing - it does sound like a good piece of kit.
 
steve_c said:
Teresa, I hope you've made clear that you'll need specialist catalytic converters that retain NOx, rather than the standard model that was fine for my 1.4. I'm sure that they'll check your existing cats before they start work, they certainly did with mine.

If your existing cats aren't working I would expect you to have the Emission Control System and EPC lights on all the time. Do you have any means to reset them while you're down there?

At the very least I'd encourage you to hang on to the discarded cats until you know that the replacements are in full working order.

Obviously I hope all goes well for you (as it certainly did for me). I'll be quite nervous until we hear your result!
Click to expand...
Hi Steve

yes, i did mention that they weren't standard, but i think i will remind them and double check before i go. I've only got the engine management light on but the only code that is showing when scanned is the Cat at the moment.

I think i will ask them if they have a guarantee as i am concerned that if i get it back and still have the eml on once it has been resent (i don't have anything to reset with), i could have spent a lot of money and find it fails the MOT in Feb

Thank you so much for your support on this T
 
Teresa said:
Took Mabel out for her first proper run since having her new EGR and Breather pipes fitted. Blimey, that has made a difference. Before, she always seemed to be pushing it a little to get her to 80. This time I set off down the bypass, not really taking much notice, and suddenly realised I was doing nearly 90!
Click to expand...

Teresa, the above quote (from the Today I... thread) suggests that your exhaust may not need such drastic attention as you expect. Have you had it checked by any exhaust specialist?

It may be that you actually need no more than a new flex section. If that was all I had needed I would have used Powerflow in Norwich: https://www.powerflowexhausts.co.uk/Powerflow-Norwich .

I didn't use them for my system because they use pre manufactured silencers and I wanted an absolutely custom system. But they have a good local reputation and it may be worth getting your exhaust checked there asap.

Because the FSI has such specific requirements for its cats, I'd be very wary of changing either of them unless it is absolutely necessary. Far better to use Infinity for a cat-back system if your silencers are starting to blow.

I've offered you the loan of my VCDS cable for when you go to Infinity and that offer stands. It would enable you to clear the warning light there and then and feel confident that it was gone.
 
Hi Steve. I do know that the cat is shot as all the bits are rattling about. The difficulty i have is that i don't know enough about the parts to have a decent conversation with a company.

I'll get in touch with Infinity and ask if they guarantee that their cats will not cause the car to fail its MOT due to the EML being on for the cat. I think that if they can't guarantee it, i will give up on the stainless steel exhaust and just go to the Audi garage and see if they can do it.

Thank you so much for all your help. Its a right pain. I wish i'd bought a 1.4
 
Teresa said:
Hi Steve. I do know that the cat is shot as all the bits are rattling about. The difficulty i have is that i don't know enough about the parts to have a decent conversation with a company.
Click to expand...

Audi no longer supply cats for the FSI unfortunately. I'd be reasonably confident that Infinity will be able to supply a cat that will get you through the MOT. Have both the cats failed?
 
Hi Steve. i don't think the back one has necessarily, but I just want to get the whole thing done really.

I've sent them a message and they are normally pretty quick at coming back to me so fingers crossed

thanks again T
 
Teresa said:
Hi Steve. i don't think the back one has necessarily, but I just want to get the whole thing done really
Click to expand...

Teresa, I understand absolutely the desire to get the whole thing done and be through with it, but the more I think about it, the more I think that may not be for the best.

You can buy the specific front catalyst you need from BM for around £120, get it fitted locally and then see whether or not you need the rear cat replaced. That route minimises the financial risk, or alternatively buy a used but sound genuine Audi front cat from bullzbitz on eBay for a similar price. The front cat for the FSI comes in two different versions, either 3 or 4 stud, so you'll need to make sure you get the right one..

If I had an FSI, I think that I'd be inclined to go with a used Audi cat to be quite honest.
 
Just to join in here, I had a Klarius rear cat(the one that sits directly under the handbrake area) fitted to mine from fleabay(£96 brand new), and nothing is showing on VCDS, I also have two front cats(that fit directly after the manifold) sitting in my garage at the moment before you go buying off overpriced suppliers on Fleabay.
My Klarius cat was delivered two days after ordering it, and to date it is absolutely fine.
I could do a front cat for £30 + postage to you, a damn sight cheaper than the one that is mentioned above!
 
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