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Failed Emissions Test on MOT and its not the JUST the Catalytic Converter - Is My Car a Gonner?
Petrol VW Golf 08 Plate. Always sailed through MOTs, regularly serviced, no advisories from last year. This year it fails without warning:
No warning of this and the car has been regularly maintained. Not driven as much since lockdown but still taken out at least twice a week.
Anyone any idea what might be causing this? No way I can afford a new car so face losing my wheels if they can't solve this. No warning at all. Car always started fine and ran sweet as a nut. If I am entirely honest sometimes when it started up it sounded a bit like a diesel but garage have spent all day diagnosing and don't know what's wrong or how to fix it.
- Exhaust Lambda reading after 2nd fast idle outside specified limits (8.2.1.2 (c))
- Exhaust carbon monoxide content after 2nd fast idle exceeds manufacturer's specified limits (8.2.1.2 (a))
No warning of this and the car has been regularly maintained. Not driven as much since lockdown but still taken out at least twice a week.
Anyone any idea what might be causing this? No way I can afford a new car so face losing my wheels if they can't solve this. No warning at all. Car always started fine and ran sweet as a nut. If I am entirely honest sometimes when it started up it sounded a bit like a diesel but garage have spent all day diagnosing and don't know what's wrong or how to fix it.
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Comments
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Faulty sensor. ?0
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The MOT emission test is all done at the tailpipe. There's no way from that to know what's happening before the cat, just what's coming out the end...
Assuming the really obvious, that it's up to temp (but that would be high CO), and there's no fault codes relating to the pre-cat lambda...
...then a dead cat is the most likely cause. One of the jobs of the cat is to oxidise CO into CO2.
What's the actual lambda, CO and HC readings?0 -
AdrianC said:
What's the actual lambda, CO and HC readings?
I get what you say about what the MOT covers but I believe the garage have gone beyond the MOT and tested pre cat in an attempt to diagnose the issue. They know I am keen to keep this on the road if possible. And the lambda sensor was mentioned on the phone so presumably they have looked at that.
I think the garage is under pressure with cars coming in all the time. This was expected to be a fast turnaround and hasn't been and with mechanics off left right and centre self-solating they are stretched to the limit and weren't expecting this and haven't allocated any bodies. So as I don't need the car have agreed to leave it there until middle of next week.
Apologies if the info I am providing is second hand and uninformative but garages tend to be very brief on the detail when explaining things to women and in this instance I can't pretend any in depth knowledge, just common sense on basic things to do with how a car operates.0 -
High lambda can be caused by an air leak on the exhaust after the cat. I had this on my car when one of the sleeve clamps to the backbox had started to deteriorate.1
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Nobbie1967 said:High lambda can be caused by an air leak on the exhaust after the cat. I had this on my car when one of the sleeve clamps to the backbox had started to deteriorate.
- Central exhaust sleeve clamp corroded
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If as you say it has a corroded exhaust clamp, then it may be drawing in air where it shouldn't. exhaust clamp for that vehicle will not be a fortune. and is a relatively simple fix.1
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