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I have a 1996 Megane and 6 months ago I put petrol in at a BP garage (not one i usually use) and within 500 metres the car started coughing, spluttered and finally died after violent misfiring and lack of power. It turned out the Oxygen sensor had burnt out.
Recently we've had all this in the news about this bad fuel and funnily enough it affects the exact same sensor and caused the exact problems i had had some 6 months previously!
Anyways, had the sensor replaced, took the car for it's MOT yesterday and it failed on Carbon Monoxide emissions. I was worried about this as in the news they said that the fuel problems recently could affect cars MOT emissions further down the line as a long term problem.
The guys at the test centre didn't know about my previous fuel problems and sai dthat it could be bad fuel thats caused the emissions problem.
UGH!
Anyways, my reading are as follows: CO % 0.72 HC ppm 404
C02 % 14.26 02 % 1.24 Lambda 1.020
It failed on the C02.
I have it booked in for a diagnostic test this afternoon but now folks are saying "oh, we might not be able to find out the problem" and i'm beginning to worry that the car might not be fixable and if it is it might cost a small fortune.
So, i guess what i'm asking is, does anyone have any ideas why it would fail on C02 emissions and any rough ideas if it's expensive to fix?
I realise it's hard to diagnose problems without having the car infront of you but i'd just like to get some ideas as to what can cause C02 test failure. I asked at the garage if the Cat would need renewing but they said it might not be that.
So i'm just throwing it open to all you guys and see if you've experienced anything like this or had any 'bad fuel' affecting your emisions.
Ta guys!
Jackie
 

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A car can't fail an MOT on CO2(carbon dioxide)emissions,but it can on CO(carbon monoxide),so I guess this is what has happened.

The CO and HC(hydrocarbons) readings are high from your post above,so I suspect that the catalytic converter in the exhaust pipe could be damaged.The Lambda is pretty much spot on,so it tends to suggest that the past events have damaged the cat internally and now it can't perform the job it's meant to.

As long as the engine isn't misfiring and no other obvious faults are present,then this is what I personally would suspect.

Let us know how you get on.:)
 

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hi jackie

try a new air filter and an oil change, you'd be surprised the difference they make to the co emissions. D'ont assume its the cat until the fundamentals of a clean engine, air intake
and clean oil burn less hydrocarbons.

cheers

zarkos ;);)
 
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