My 1.8T Failed MOT/NCT on emissions and also has high fuel consumption.

JamieOS · Mar 9, 2019

My A4 1.8T 163bhp BFB failed its NCT (Irish MOT) on its emissions. I've put a photo of the results below. You can see its got high carbon monoxide levels. Any idea what might cause that? I've tried scanning it with VCDS for fault codes and nothing is showing up.

Another issue the car has is its thirsty. Its doing about 280 miles to a tank, which is similar to my modified B5 S4. Not sure if its linked with the emissions issue.

Any advice would be greatly appreciated.

Leo Komninos · Mar 9, 2019

Try terraclean, worked for me.
Or
I would run some paraffin through to clean, but that's me.

Then put higher octane for test.
Luckily I have a Lpg, and can now get away with having test done while on Lpg, at the council mot test centre in Birmingham.
Hope you have a good result.

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JamieOS · Mar 9, 2019

Cheers for the reply. There isn't anywhere near me that does Terraclean. We only have one type of petrol available at most pumps where I am, and I always use an octane booster, so it should be alright in that sense.

Leo Komninos · Mar 9, 2019

I'd check the notorious pcv systems that VAG have, pipes usually break and can be a cause.
Depends on how envoled you get.
Pull injectors and clean, change air filter and fuel filter.
Check codes with vag-com, ect.

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Rich76 · Mar 10, 2019

I have my mot this week and have just noticed the idle is not as stable as it was so when it stops raining I’ll be removing my Pcv and cleaning it up
Then check the air filter and map sensor might also take the plugs out and check them over

pauldazzle · Mar 10, 2019

Coolant temp sensor would be my first suspect.

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My 1.8T Failed MOT/NCT on emissions and also has high fuel consumption.

JamieOS

Resident Eejit

Leo Komninos

Registered User

JamieOS

Resident Eejit

Leo Komninos

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Rich76

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pauldazzle

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