2006 IS250 MOT emission fail

[Andrii]

Hello, just returned from a garage and a bit lost. Nothing was showing a problem  - no one Check Engine during a year I have the car, but MOT failed because of the emission.

They changed sparkle plugs, played with sensors a few days etc. and now believe it's because of one catalytic converter (not 100% sure which one).

I use Shell E5 and did some miles on a low gear before the test, but here I am.

What are my options, if any? I like the car and don't want to sell it (it's also not fair).

[scudney]

You could also try something like Bg44K and see,it might help 

[Spock66]

What specific parameter did it fail on and how far out?

Sometimes an oil change will help, particularly if the car is used on frequent short journeys which can cause fuel/oil contamination.

[Bluemarlin]

You could also try a bottle of Cataclean. I remember using that once to get me through an MOT when I had a dodgy catalytic converter.

[Andrii]

Thank you for your answers. The oil was changed 2.5k miles ago. Cleaning solutions - could be.

[NemesisUK]

Sounds like it needs a good "Italian tune-up" immediately prior to the test. Take the car out for some high (legal) speed running at high revs and strong acceleration for a good 30mins

[Linas.P]

What is the mileage? Because if it is ~75-100k, then it my be the case of O2/Lamda sensor failing and car simply running rich which would blow emissions out right away. Catalytic converter failing very unlikely before like 200k miles, but catalytic performance would show as bad if O2 sensor is bad. 

[Mr Vlad]

Have you noticed that your fuel usage has increased? Another way of putting it is has the cars MPG got worse recently? What kind of mileage do you do in a week? Have there been any lights come on in the dash display?

[Andrii]

@Linas.P, @Mr Vlad I'm on 111k miles now. They told me that the sensors are ok, no leakage etc. I didnt see MPG degradation and no any lights on a dash.

Finally it can be considered as solved this time - it passed emissions after hydrogen carbon cleaning and on the hot engine.

The emission results before: Fast Idle CO 0.83; Natural Idle CO 0.39

After the cleaning on the hot engine: Fast Idle CO 0.00; Natural Idle CO 0.29 (limit is 0.30).

I have a mixed cycle: some motorway + some town miles.

What I noticed after the cleaning  - MPG improved from 30,7 to 35.

Thank you all for your suggestions, will monitor her MPG. Hope the new tank doesn't get any worse.