Failed my MOT on CO2 emissions car passed everything else. It has to be under 0.3% and mine after being tested numerous times was running at 0.9% which is way over. I rang blueflame as I have the turbo back exhaust with 100 cell cat and they said it could be the lamda sensor or the cat?? I am pretty annoyed as I thought it would go straight through as it is a 55 plate with 22,000 miles. Has anybody else had this problem?

My old mk1 could barely pass the mot with a 100cel cat, and then it needed the engine to have been really hot and been driven hard for several mins before the test.

If the car was left to cool to much it would fail by a considerable margin, I wonder how long yours was standing before being tested.

Ouch, sounds a bit costly to get it through now. 100cel cat have much to do with it only i think i have seen this prob around the forums with 100cel cats before?!?!?!? though i maybe wrong

Mine was close but passed

An MOT friend told me when i had a problem on a car that was failing on the exhaust emmisions to put in double the amount of redex to recommended and take it for a 50 mile burn, push it hard so you can clean the system and remove crap.

when you do get back to the mot station keep it running.

When i emailed BlueFlame they sent one back saying that they only do 200cels cats now

Is this true?

It seems that every now and then this subject pops up about cars failing their MOTs because of the cat

I want a BlueFlame Turbo back for mine but if this problem keeps arising now im having doubts

An MOT friend told me when i had a problem on a car that was failing on the exhaust emmisions to put in double the amount of redex to recommended and take it for a 50 mile burn, push it hard so you can clean the system and remove crap.

when you do get back to the mot station keep it running.

Have you tried this yet?

i have a very cheap 200cel Cat from the States in mine, passed no problem for the second time this year.. it will have to be properly hot to stand a chance.

Are you certain there is no chance of an air leak between the engine and lambda sensor? That would artificially force a rich mixture.

Do u get any fault codes logged in respect of Catalytic Converter System efficiency? I regularly get that, it seems to tie in with periods of extended idling when the Cat can cool down too much to work properly and the rear lambda sensor throws a benny, never turns the engine light on, just sets the code.

No air leaks on mine Rich.

My 100 cel cat logs as Catalytic Converter System below efficiency & turns the engine light on after about 80 miles of 'soft' driving.

With the loud pedal on ,,,,, it don't happen!

Interesting fact has emerged here, if it's cold, it will fail.

After several attempts on the CO2 measurment lark, the reading got lower each time!

May try the Redex lark though.

Have you tried this yet?

yes on my astra mk4 that i had. the following year was worse so the mechanic gave the lambada sensor a quick clean too. cant remember how far out it was but the main problem i had the first time was the cat needed replacing as it was shot away after the car had a problem of misfire which blew the cat apart, certainly cheaper than replacing it and worked.

It is surprising how many minutes even a standard Cat may need at 3000rpm offload to get it hot enough to light off and work, a lot of garages are just not patient to wait long enough :( it's easier to say it failed and needs a new Cat.

Because of the way it works, it's not a case of the readings dropping gently as it starts working, it will often be way out then suddenly drop as the Cat gets hot enough and lights off. The lazy MOT tester will see the readings not dropping after a couple of minutes and call it a fail.

It will always help if you are able to give it some on the way to the test station and get the test done as soon as possible while the heat is still in the Cat.

the joys of while you wait mot places

the joys of while you wait mot places

Or the joys of a 'friendly' MOT place.

Or the joys of a 'friendly' MOT place.

i personally couldnt comment

looks like it might be worth giving it the beans then taking it straight for emissions test and then hoping that it just passes.

Good luck!

Let us all know if it passes:)

Its got along way to go to get down to 0.3 but good luck.

What's the air filter like?, have you considered trying a fuel system cleaner?

Also you are getting your CO2 (Carbon Dioxide) and CO (Carbon Monoxide) confused. CO2 for VED banding and CO for emissions.

I wounder if using 99 octane petrol would help the emissions?

I use shell v power already and I use STP fuel system cleaner in the silver bottle so not sure what else I can do apart from get the cat super hot. Thanks fordfan yes i just realised that it is CO rather than CO2!

I'm putting my stock 55 vRS through for its first MOT tomorrow, you've put the fear of god in me now!!!

should fly through mate,being stock and on a 55plate

I wouldnt worry

.... there was me hoping to have an excuse to give it a "gentle" drive down the motorway tomorrow

You still can!

Gentle tho of course!

I have Blueflame turbo back and could not get through emissions until I changed the lambda sensors. Now goes through ok.