MOT Failure: CO Levels during Fast Idle

[b-force]

As above. During the natural idle test the level sits at 0.06%. This seems very good seeing as the upper limit is 0.3%. However on the fast idles it read 0.7% then 0.48%.
I've replaced the lambda sensor, done a full engine flush, oil & filter change, injector cleaner but still the levels are over. I'm going to check the plugs and replace if neccessary. Is there anything else that is particularly prone to failure on Sportings?
All sensible help appreciated.

[Tom]

Dodgy cat?

[P HUGE]

you know the hassel i have had with mine, is it just reading over on the lamnda or the co2 aswell! check for any leaks in the exhasut from the manifold to back box! aswell as any leaks on the block istelf!

i had to rebuild the bastid!

[Cat]

I had this too. No matter what they did the reading was too high. We 'came' to an arrangement in the end.

[jimma]

I had this too. No matter what they did the reading was too high. We 'came' to an arrangement in the end.

Did you come together, or just the mot tester?

Is the cat shagged Bum - and was it hot when it was tested? That is a trick that usually works.

[Cat]

Did you come together, or just the mot tester?

Hahahaha, urg no! he's about 70.

[hf turbo]

try a fuel additive

[xploitGT]

make sure the cat is warm perhaps. I cant really suugest much more as you have eliminated the posibilties.

[CaL]

Try higher octane petrol?

[pkelly23]

Just a quick question - will i have to put my GT back to standard for its MOT?