Just had my car in for MOT today and pleased it passed, however looking at the emissions results it seems that the carbon monoxide emissions were only just below the limit of 0.2% vol with a value of 0.19

Looking at last years mot the readings were 0.02% which is significantly lower. Looking online it seems to suggest that the main cause of high CO emissions is a lean mixture possibly caused by a vacuum leak. The car has an intermittent fault code of PO171 which shows as 'system too lean bank 1' which comes up every few months of driving. Another thing that happens is when first started in the morning, the car stalls by itself as you try to move away with low revs.

I've checked the main brake servo pipe which seals well and was replaced recently. Can't see any other potential splits in any pipes.

Just wondering if anyone knows if this is a higher than usual reading and if i should be worried

Edited 5 June, 20179 yr by clarendon462

My engine wanted to jump out of the engine bay on start up, I replaced the Brake Servo Vacuum Pipe, it's about £35.00, it's a common fault for them to crack on the joints especially on the non-return valve. It now starts up as normal.

 

DB.

As I said it was replaced recently due to that fault

Can't remember if it was you or someone else that checked their PCV valve for a leaking diaphragm?  If it wasn't you, see if there's a suck on the little equalisation port on the side of the plastic housing when the engine's running.

 

How many miles has it done? Burn any oil?

Edited 5 June, 20179 yr by Wino

Hmm it might have been cause ive asked about the other issues before, no there is no sucking on the pcv valve hole. Its 108,000 miles and uses a tiny amount of oil every few months