Hello, My car failed its MOT on Saturday due to high Co2. I have ran it through with some Cataclean and got it checked again this morning, sadly CO2 still high. I have got a new set of spark plugs to fit, will clean the MAF tomorrow and fit a new MAP Sensor too. I noticed that the Boost Pressure Control Valve (N75) was damaged and one of the pipe loose. The car is running rich but no misfire or stalling.

 

As this is my first Skoda, I have some questions and would be grateful for any help I get.

Do you reckon that the damaged N75 valve could be causing the rise in CO2?
Can anyone recommend a good workshop manual which also covers the 1.4 VRS?

I have been struggling to locate the MAP sensor, does anyone know where it is located?

 

Thanks in advanced for your help

 

Its possible that the N75 is causing issues, difficult to say really, usually it's a misfire, although you may not "feel" it it may be happening hence not a clean burn and then increase in emissions

 

Workshop manual, well VW's own which is called ETKA and is available on one very popular auction site.

 

Heres a PDF of the TSi engine, will help locate things and explain which sensor does what and more importantly if it has a backup strategy.

 

Don't forget to change the air filter to in my opinion......how high was the CO ?

 

An oil and filter change won't hurt either especially if you dont know how old the oil is

 

Last but not least drive it like you stole it on the way for emissions test!!

 

1.4TSi.pdf

Mot tests for CO emissions not CO2

 

If you bought the car 2nd hand then check it hasn't had the cat gutted (a de-cat) or replaced with a "sports cat" (mostly fake junk) or even removed completely. The MOT CO test is not at all demanding of a CAT (no load, idle and fast idle), any functioning CAT should pass easily and is not affected by engines running slightly rich.

 

If your car is a heavy oil burner, it may have killed the cat.

 

You will require the CAT replacing to pass IMO.

It is pretty common for MK2 vRS Fabia to fail a MOT on the emissions and also not having sidelights at 'Test Centres' that are not Skoda Main Dealerships ones.

 

I have been told the cars had a de-cat etc, when actually they were dead standard.  Engine / ECU / Exhaust System.

 

Amazing how new plugs, air filter, 99 ron petrol and tested right after being fully up to heat before going into the test centre and tested right away makes a difference 

(EDIT, i see i had one that was going to have a fail with a APR switchable re-map.)

Odd how a 'Skoda Dealership test bay also makes a difference where a car that fails elsewhere can pass in their test bay......

Jolly bad show as far back as 2013 if a 3 year old car was failing and Skoda had them in a higher VED band than the Sister cars from VW, Audi & SEAT. (the Cupra went down a band in 2013)

If one fails there, then there should be a master tech not far away that knows why that should be happening..   They will also know the DRL unit is the Sidelights.

 

@xman

Years back a member was rightly giving thought to Twincharger Oil Burners and cats / MOT's.

They were right to be worried.

Lots of Twinchargers got replacement engines some more than 1 replaced engine and some got a new cat and some did not.

Luck of the draw and as it should have been all excessive oil users should have had new cats as well as new engines at VW's expense.

Chickens can come home to roost...

http://briskoda.net/forums/topic/268168-vrs-mot-issue

 

 

 

 

Edited 17 July, 20196 yr by Roottootemoot

Mine sailed through emissions as it should if everything is right.

 

Did get asked about the sidelights to, although I knew the guy testing and explained.............but still wired up the sidelights anyway, much better using the bulbs that were sitting there doing nothing, looks better to !!

?

Do you still have the DRL units on dimmer as a sidelight then just to annoy some drivers that think they are fogs?

(and used singularly as parking lights.)

It's exactly as it was before, just when you flick to sidelights, the DRL's dim and the top ones come on as they should have done from new.

 

All pinned and wired into existing headlight looms for a factory install

Thanks guys for the advice, etc. Retest booked for next Tuesday and I am getting the Cat checked this Friday.