Is200 Emmission Fail On Nct 2Nd Time.

[mDx]

Hello everyone, just back from the NCT centre and failed emmisions once again.
At low rev's its below 0.30% its only 0.05%
At High rev's its above 0.20% got 0.25%
And yes car is Serviced, oil filter air filter new oil, new spark plugs.
The tester questioned me if its not running rich, wictch i think it is a little. He sayed your both low and high rev's is running crazy, changing numbers every sec. I mean sometimes it get mad high Co like 0.70% then goes back and so on and so for.
However my lambda is 1.00 Which is good and HC 56 which is good aswell, he has no clue aswell what could it be, he only gave me advice that i have to go to bosh, but i want to sort this out me self, Maybe its running rich? How can i check? Volt meter? Or just try to clean the sensor? I did got error before but i removed it with computer. I think it was bank 2 something. And I did see that the one of the pre cat's is burned a little. But it couldnt fail me nct yet. Should i check sensors? What other problems it might cause, need this sorted till 13/03.. Don't want to give up lol.

[mDx]

Bump no one has a clue whats goin on?

[aviator888]

I would start from simple and cheap things (new spark plugs;oil&filter change;high octane petrol;new air filter;clean the O2 sensor followed by a good blast on motorway just before the next test). If all that does not work then it could be many things from CAT converter to leaky injectors etc.. Start changing and eliminating one by one.

Also i recommend trying different garage for NCT next time.

[mDx]

Okey will do, checked today all o2 sensors on computer, and i didnt get a voltage on one of the sensors bank 1 sensor 2 thats seems like after cat sensor. I did got the engine management light before but deleted it ages ago and never appeared again. It came because i had a big hole before the cat, i think. Should i replace o2 sensor after cat? does it do anything to make emmisions change? I thought only the precat sensor does the job, the other one just measures the oxygen?

[aviator888]

That sensor does not affect emissions.

[mDx]

But i think it does tell that the cat is in trouble if it doesnt do the job i am sure?