hi all, 

 

I two days I have my MOT test, and unfortunately yesterday the engine light came one. After connecting the CARISTA reader, it became clear the issue is with the EGR valve..Again 😞   Two year ago the EGR valve was replaced, meanwhile I have done about 15k miles only , mostly long distance drives, but also some city drives (15mins usually).   Engine has 165k miles on the clock, 2.0 CR TDI 170, Superb 2010.

Either way, the car does not have any loss of power, just like previous time.   So I thought of using EGR cleaner through air intake, hoping it will help to clean the engine/EGR enough before the test...The fault can come back the day after, I don't care....

Has anyone here try the cleaner before?  Does it help to pass an MOT?

Thanks.

I'd be very surprised if a spray in the intake makes any difference, but apart from the price of the item, you haven't much to lose by trying, I think.

Can you not clear the fault code just before setting off for the test?

 

Indeed, no harm trying...

I have tried clearing the code today, it just comes back after 1 cycle..I will clear the fault at garage before handing over the keys, but if they restart engine not once but twice, the car is doomed to fail MOT.

I assume the MOT will fail on Monday, so that gives me a wild card to attempt anything trying to fix it temporarily until then...Some of the wild ideas are:  EGR cleaner spray,  replace airflow sensor,  blow compressed air through airflow sensor tubing, hoping it will clear out soot.

 

I have a sliver off hope the EGR airflow sensor is actually broken...it would not be the first electrical fault on the car..The list is endless:   Dashboard back lights, airbag sensor wiring in the door loom (last week), indicator in mirror (last week), columbus (2y ago), AC air quality sensor, EGR airflow sensors (after fixing previous EGR).  Considering all previous electrical issues, it's really odd coincidence that after disconnecting and reconnecting the battery last week, that the EGR fails.
 

TBC  for sure.

Did you get it fixed?

 

if not I have a lead to sell that works to tell the ecu the egr is working even if it isn’t. As long as your engine code isn’t CBBB, which is the earlier engine with egr at the front of bonnet and not the back.

It did not work, though the engine does run smoother nonetheless.

 

Emissions test on Mot was ok, even with engine light on. However, Mot failed for engine light.

 

It tells you how useful an egr is for emissions 😉. 

Either, I have decided to not fix egr, and just get different car next year.  Too many things start failing on the car.

The type of emissions that EGR addresses isn't one that MOT measures. Namely NOx, oxides of nitrogen. Poisonous to things that breathe.

 

Thanks...learned another thing today.  So is it the DPF that then captures the NOx and burn it off later or has the DPF another function?  And what does exhaust do, chemically? 

No, the EGR, when working is what prevents most of the NOx formation, by changing the combustion conditions and constituents.

 

DPF is mainly about catching particulate matter (soot). That is the only measure in MOT, at present, for diesels.