BMW Incorrectly Failed By Tester Emissions Lean Burn

I told the garage that fitted the CAT that it failed due to high emissions and showed them the results of the MOT. They hooked it up to the diagnostic machine which stated therewas an error code related to the CAT but it was not serious enough to cause the engine management light to come on.

The first mechanic said that he did not think there was anything really wrong with the car and if I paid for the MOT again (with them this time), they could pass it for me. But they certainly had not identified that the incorrect engine code had been put in at the original MOT centre. A second mechanic (more senior) then came in and stated it needed a new CAT and that was the reason for the high emissions. 

I agreed to the new CAT I was given the impression it did need replacing and was faulty. 

As mentioned the car should never have failed the MOT in the first place and the original CAT was fine. 

Is there any evidence that there was a 'cat error' from their diagnostic report, fault code etc?

Hi Grob
Thanks for visiting the forum and sorry regards the grief .
The problem stands with the garage that fitted the cat ,the mot is not a diagnostic tool its only a basic inspection.

(Assuming the vehicle failed on lambda,the link attached, the engine code relates to engine code which has high lambda threshold)

Yes you have had a print out which says its failed but chances are the tester has used the wrong vehicle limits regards the mot which in itself is also a problem.

The garage that fitted the cat should of carried out a diagnostic check to ensure the cat is performing ,very easy job if you have the correct equipment.

A fault code may come relating to a cat fault but all that code does is to point the technician in the right direction which in this case is the emission control system which includes sensors fitted to the exhaust and engine,any of them could be at fault .
Any garage or technician worth they salt should satisfy themselves through they own diagnostics to come to a conclusion if a fault is present and the part needs replacing and certainly not by what someone else has said.

If someone give me an mot emissions print out that states too high of a lambda and the person also says the cat is faulty ,then that would be false as a catalytic converter has no control over lambda readings what ever they are.
Both parties are at fault here but the mot garage did not diagnose the problem as really they was no problem,human error was the mistake.

A majour issue with a catalytic converter will put the engine malfunction lamp on no doubt about it,yes it's had what we call soft/pending fault code related to the cat but the garage have proberly just interpreted the fault code wrong and just because the fault code had the word cat in it have just assumed its the cat that the problem.

My advice would be to get back to the garage that condemned the cat and get your money back based on faulty workmanship and wrong diagnosis.

I don't see how any garage could think there's an issue with a CAT with CO/HC readings like that.

It should never have failed the first mot test on emissions - I'm afraid to say a tester hasn't followed the correct procedures, and your problems have evolved from there with the second garage being just as culpable - Mind you if it was tested correctly in the first place, then you'd have had no problems.

The cheapy cat is working fine - However, I would do what you're doing and get the original cat put back on, there is nothing wrong with it and it will be much better quality than anything Euro can supply.

You shouldn't be paying anything out to anyone in my opinion.

Seems you are getting mugged off by everyone concerned, both garages don't know what they are doing and it should not have cost you a penny more than the mot test seeing as their is nothing actually wrong with your car.