Nct fail on emissions (high idle CO reading)

paulb06

Hi all, just looking for some advice here if possible.

Car failed nct on emissions, Lambda reading was OK, CO reading on high idle not so much.

The reading was 0.97% and a pass is below 0.20%. I've been to my mechanic and he says it needs a new cat.

Are there any other ways around this as a temp solution to pass nct? I am thinking of trading the car in but don't want to put €600/€700 into it beforehand.

Its an Audi A3 1.6 petrol year 2004.

Thanks in advance!

paulb06

Photo of the readings attached.

nd

Could you just check the air filter or say when it was last changed?

The very high difference in co reading between idle and high idle would suggest an air restriction. As well as the lambda reading.

paulb06

nd wrote: »

Could you just check the air filter or say when it was last changed?

The very high difference in co reading between idle and high idle would suggest an air restriction. As well as the lambda reading.

Hi Nd, I would hazard a guess and say the air filter was changed in my last service, which was 3 months ago. I have recently noticed that it takes a little longer to take off in my car, as in it's taking longer than usual to get from 0-60, like its not using its full power. Not sure if this gives any clues?

My mechanic is of the opinion that the cat needs to be replaced but this may not even bring it down to pass rate, the engine is burning a lot of oil so he recommended getting the cat replaced and literally go for the nct after and see how it goes.

soap1978

try this stuff,very good Dipetane

Waterson

If it is burning a lot of oil, the new CAT will get just as contaminated. But according to this read out, I doubt it. The (HC) hydrocarbon levels would be much higher. Engine oil is a mix of hydrocarbons. Look also at the low idle readings. They're excellent.
Your lambda reading is indicating a rich air/fuel mix. Has your mechanic checked fuel trims, would be interested in seeing what these were before condemning your CAT...

paulb06

Just an update for anyone interested, after been told that I needed a new cat from the mechanic I usually use, it wasnt the case. Got the issue sorted for less than €100 and it flew through the emissions test today!!

Anyone want details of the guy who sorted it for me send me a PM. Can't recommend him enough, he diagnoses the actual problem and takes out all the guesswork.

Polo_Cluvie

That's great. Out of curiosity what was the actual problem?

paulb06

Polo_Cluvie wrote: »

That's great. Out of curiosity what was the actual problem?

It turned out to be the EGR valve, so much cheaper than the cat which I was told was the problem by the mechanic I usually go with. Worse thing is if I got the cat replaced it still would have failed emissions...really worth removing the guesswork to find the real problem.

Hogey1

Could I have the name of the guy that fixed it.

paulb06

Hogey1 wrote: »

Could I have the name of the guy that fixed it.

Pm sent

biko

You have your own thread Hogey, https://www.boards.ie/vbulletin/showthread.php?t=2057839069
I am closing this.