2008 W245 B200 CDi MOT Failure - Emissions Test failed

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Borris1954

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My daughter's 58 plate W245 B200 CDi failed its MOT a few days ago on a split CV boot (which is easily fixed) and Exhaust Emissions being too high. I completed a full service a few weeks ago in readiness for the MOT and I am now kicking myself that I missed that split boot! When I serviced the car I connected my Star system to check for any fault codes and at that time the only DTCs present were that all 4 glow plugs have failed. I know they can help reduce emissions for a cold engine on start up but should not be doing anything useful once the engine is hot. However, when I serviced the car I also noticed that the thermostat now appears to be faulty as it takes forever to reach normal operating temp and I suspect it may have been this way for over 12 months. Given the car is only used for local short journeys I am thinking that this may be the root cause of the emissions issue. i.e. Lots of short journeys with a cold(ish) engine and no glow plugs has resulted in a pretty fouled up EGR system and maybe even CAT.

Has anybody experienced this type of issue and how did you resolve it.

Thanks
 
The thermostat has failed and will need replacing, an easy diy job, and will have an effect on emissions. I suspect the main cause, as you rightly surmise, is using a diesel for predominantly short journeys. Put some diesel fuel system cleaner in the tank (Millers, Wynns etc.) and take it for a good thrashing.
 
Diesel's need to be as hot as you can get them before they are tested for emissions. A failing thermostat will cause cool running and possible emissions test fail.
 
Diesel's need to be as hot as you can get them before they are tested for emissions. A failing thermostat will cause cool running and possible emissions test fail.
Exactly this, the MOT station we use always tell us to drive around before the test is due, make sure the engine has reached full temperature.
Once with my BMW 320d I was told to take it up and down the bypass with a degree of enthusiasm.
 
The main issue for the higher than plate value smoke opacity emissions is 100% the faulty thermostat .

What's the plate value and what was the test mean value ?
 
Thanks for all the responses which point in the same directions as my thoughts.
I have ordered a new thermostat and have everything crossed that together with a suitable cleaner additive and an "Italian Tune up" the issue is resolved. When I next have access to the car I will run the Star EGR test and if that shows anything pull the EGR for a scrape and general clean up.
 
Forgot to say plated value is 1.3 and the average during the test was 1.32 so it was close but no cigar...
 
These pre DPF plate values are all over the place , you can even have a 2003 1.9 turbo charged derv that's 0.60 !!!
 
These pre DPF plate values are all over the place , you can even have a 2003 1.9 turbo charged derv that's 0.60 !!!
My old pre-DFP 05 straight 6 3.2L had a plate value of 0.6! WTF!
 
Out of interest I have just been reading the relevant section of the MOT Inspection Manual (MOT inspection manual: cars and passenger vehicles - 8. Nuisance - Guidance - GOV.UK) which appears to say if the Tester can't locate the manufacturer's plate value they should use the following:

Before the test, check the maximum smoke level limit for the vehicle and enter the required details into the diesel smoke meter.

The maximum smoke level limit will be the level displayed on the manufacturer’s plate; or where there is no manufacturer’s plate information:

For vehicles first used before 1 July 2008, the maximum level is:

  • 2.5m-1 for a non-turbocharged engine
  • 3.0m-1 for a turbocharged engine
For vehicles first used between 1 July 2008 and 31 December 2013 the maximum level is 1.5m-1 for all engines.

For vehicles first used on or after 1 January 2014 the maximum level is 0.7m-1 for all engines.

I wonder how many owners have obliterated that plate to give a bit more headroom on the test...
 
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A 2009 Ford 1.8 tdci plate value is a whopping 1.75 so the lower 1.50 default is applied .


20180203_101111.jpg
Pops had this random 0.51 sticker all by itself underneath the bonnet , didn't have a clue what it was at first then the penny dropped come May 2018 .
It's not there anymore , the pressure washer took care of it !
 
Pops had this random 0.51 sticker all by itself underneath the bonnet , didn't have a clue what it was at first then the penny dropped come May 2018 .
It's not there anymore , the pressure washer took care of it !

Now just where did I leave my pressure washer...
 
Just to close this out. The car has now passed the MOT. The CV boot was actually OK but had just lost a clip so turns out I didn't miss a split after all! Although STAR diagnostics showed 4 DTCs for faulty glow plugs following the diagnostic test further revealed a faulty glow plug relay was the issue as all 4 glow plugs checked out OK at about 2 ohms resistance. A dose of Forte Diesel treatment followed by an Italian tuneup and an MOT pass with no advisories was achieved.
 

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