MOT emissions fail after secondary cat delete

[BTB 500]

This is the first MOT since the cat delete.

Having no cats at all (where a car was fitted with them as standard) is an automatic fail now, regardless of whether it meets the emissions test or not.

 

[C43AMG]

That's a pain !!

 

[Charles Morgan]

Oops.

 

[IanA2]

I hope you kept them.

 

[BTB 500]

Nope.

 

[IanA2]

Nope.

Commiserations. That's a serious pain.

 

[Charles Morgan]

Double oops.

 

[martyz]

Try some higher octane fuel,and Redex or the likes,know it's not recommended by mb,but it will give you lower emissions.

 

[flango]

mmmm Who did the secondary or rather primary cat delete I would say they are at fault not knowing their primary's from there secondary's any chance of recompense there? It just shows there are people who know what they are doing and people who think they know what they are doing, that's why i'm fussy when it comes to exhausts as most places you talk to don't have a clue and have no appreciation of the effects of removing components using different pipe diameters etc.

You'll have to put something back as if they are supposed to be there it will always fail the test if they are missing since the new regs came in. You could always put what look like cats back in and map the engine to pass the emissions then map back but that one depends on the sophistication of the ECU which on my 230k is as basic as you can get

 

[tanuie]

R129 MOT faliure

Hi Bill, can I ask the reason for removing the cats
in the first place, is there anything to be gained
from this.
Thanks.

 

[Dee-124CAB]

So the fail sheet says it failed because of NO cats and emmissions levels?

 

[BTB 500]

So the fail sheet says it failed because of NO cats and emmissions levels?

Yes. 5 fails listed: CO levels excessive at both idle and fast idle, hydrocarbon level excessive at fast idle, Lambda reading outside limits at fast idle, missing cat(s).

The place that did the exhaust work still had my original cats and offered to re-fit them FOC or fit sports cats (not FOC, but with some discount). Going in to have the sports cats done on Tuesday, dealer will re-MOT afterwards (just checking the fail items) FOC.

 

[BTB 500]

Hi Bill, can I ask the reason for removing the cats
in the first place, is there anything to be gained
from this.
Thanks.

A bit more noise, simple as that! The stock system is very quiet, even at high power you mostly just hear induction and mechanical noise.

 

[Sp!ke]

No wonder it sounded so good with no cats and only a single backbox.

Good to hear that the exhaust company will refit. Will you be fitting sports cats or rewelding them back in?

 

[John]

The place that did the exhaust work still had my original cats and offered to re-fit them FOC or fit sports cats (not FOC, but with some discount). Going in to have the sports cats done on Tuesday, dealer will re-MOT afterwards (just checking the fail items) FOC.

That's decent of them albeit making up for their mistake.

 

[IanA2]

The place that did the exhaust work still had my original cats and offered to re-fit them FOC or fit sports cats (not FOC, but with some discount). Going in to have the sports cats done on Tuesday, dealer will re-MOT afterwards (just checking the fail items) FOC.

Excellent

 

[BTB 500]

Will you be fitting sports cats or rewelding them back in?

Sports cats - too much time and hassle so far to just put it back to the way it was!

 

[mr tibbs]

Good lessons to be learned from this thread, well done and thanks

Keith

 

[flango]

Sports cats - too much time and hassle so far to just put it back to the way it was!

Word of warning most cars we tested with sports cats on Failed the MOT including SWMBO Audi A8 had to swap them back for original type cats. If you fit sports cats you will have to remap if you can they are not plug and play. Also if the sports cats are of a different shape / place to the originals some MOT testers will still fail them. As the original place removed all your cats and did not know this I would be very wary of any advice they give on sports cats.

We fitted sports cats to Subarus , Evos, MB and loads of others all would have been MOT failures on emissions without a remap.

I'd hate you to spend a load of money and be back in the same position

 

[Sp!ke]

I also wonder about the longevity of some aftermarket sports cat - even if it gets through the first MOT, how many subsequent years will it pass for.

I would be erring on the side of welding the original cats back in myself as long as they do a reasonable job of it. It should be pretty easy as the could just sleeve it either end.