Audi A4 carbon monoxide excessive

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Tue 6 Mar 2007 16:47
Audi A4 carbon monoxide excessive - stokie
My 96 'N' A4 1.8 petrol (non-turbo) has just failed the MOT with CO %vol .547 - the limit is .300

Also the lambda failed with 1.031 - limit is 1.030

The garage will investigate on Thursday, but kind of hinted that suspicion lies with the catalytic converter.
The engine was new 3 years ago and uses no oil at all. The cat doesn't tinkle like I've heard on some Audis, but I'd say the exhaust has got a little noisier recently.

A cat is approx £90 from GSF. Would Backroomers replace the cat as a matter of course, or is there there any other likely cause?

BTW I forgot to do the italien tuneup before dropping the car at the MOT station.

Thanks
Stewart
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Tue 6 Mar 2007 17:27
Audi A4 carbon monoxide excessive - Falkirk Bairn
My Honda failed MoT emissions on CO last week -

Garage, who also service the car took it for an Italian Tune-up - "45mph in 2nd around the block" was enough to drop it down by roughly the same amounts as you are looking at.

Passed the MoT Emissions 10 mins later.
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Fri 9 Mar 2007 14:33
Audi A4 carbon monoxide excessive - stokie
Thanks FB.
Turned out to be the lambda sensor itself at fault. The garage charged me £79 inc labour and VAT to fix.
Will I get more mpg (all other factors being equal) now my CO is below the limit?
Put another way, does excessive emissions mean excessive fuel being burnt, assuming the cat's working correctly?
Stewart
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