Technical High CO at MOT

[Raukstern]

Hi guys,

My ´96 has 5 times the allowed CO-readings at the latest MOT, and did not pass.
Has anyone here the same symptom?
Cat? Lambda?

The car runs fine otherwise, nothing to suggest any machanical issuses.

 

[Wiltshire Chris]

My B should have failed its MOT last year on emissions but the inspector passed it on the understanding that I would change the cat. I changed it and it passed this year so presumably it's all OK. I've no idea which emissions it failed on last year though

 

[The Panda Nut]

I think cat is probably the culprit too.

 

[AndyRKett]

The Catalytic convertor contains the catalyst (platinum and palladium) that oxidizes CO combining it with O2 to make CO2.
If its reading 5 times its allowed limit and the car is a 96 without ever having had a new Cat, then its almost 100% guaranteed the catalysts within the convertor have now been spent and it needs replacing.

Good news, the old one will still be worth a lot for scrap, bad news the new one will cost a fortune right now as many of the materials used in them comes from good old Russia.

 

[shaun]

Catalytic converters on eBay under £100

 

[Wiltshire Chris]

I know it's UK but I went for the BM one from these guys

Search - Cats2u

Lowest Price Guarantee. Search - Cats2u. Every Catalytic Converter and DPF is covered by a 2 year guarantee.

www.cats2u.co.uk

came about the £100 price that @shaun quoted

 

[s130]

As an aside comment wrt CO and MOT then older pre CAT vehicles and as far as I can understand later vehicles with CATs do have a degree of MOT tester REVs discretion.

The Strada Abarth 130TC (twin dual = 4 performance carburetors) had manufacturers official CO levels at or above the current UK MOT limits. This means that for MOTs I have to lean off the mixture. Even then with the engine not running well it can still fail MOT CO criteria. HOWEVER the MOT tester is allowed and entitled to raise idle RPM to around 1200 to 1500 rpm (Note! I need to check the actual limits) to see if this then passes the CO limits.

Sadly many MOT testing stations do not appreciate/understand what they are entitled to do and will just fail because "the computer says FAIL". This makes me very mad. If our"B" were to fail MOT CO then I would press for an elevated idle RPM rerun.

In the OP's post he indicated 5 times permitted levels so I doubt an elevated RPM test rerun would pass.

I doubt many people know about the permitted elevated RPM allowance so dare I say dishonest / work hunting garages will just fail the vehicles so they can get some repair income etc.

And as for electric vehicles ..... a time will come when your vehicles idle energy consumption / (other criteria) will be MOT deemed to be unacceptable etc. and you will fail your MOT! A long stretch of imagination I know but your politicians know so much better than you!