MOT DPF changes now expected in May 2018

Test update to come into force next year to combat flaws of the current visual DPF inspection requirement

MOT DPF changes now expected in May 2018
The current MOT is failing to identify many cases of DPF removal because it only includes a ‘visual inspection’ of the hardware. Image: Bigstock.

MOT changes designed to make it easier for testers to detect vehicles with failing or removed DPFs are expected to be introduced next year, the Department for Transport (DfT) has told GW.

From May 2018 the smoke test limit for Euro 6 and some Euro 5 diesels will also be halved.

In a statement obtained by GW, a DfT spokesperson said: “We are taking strong action to stop the removal of DPFs.

“We expect future changes to the MOT emissions test for diesel vehicles, due to come into force by May 2018, to make it easier to detect vehicles with failing or removed DPFs.”

Unfit for purpose

The DVSA say 1,800 cars have been caught without a DPF since 2014 but experts believe the number is much higher and suggest that the current MOT visual inspection is unfit for purpose.

While it is illegal for drivers to use a car with the DPF removed, it is not illegal for garages to take them out.

Some workshops are known to offer removal services with the claim that removal will improve the vehicle’s performance, or is cheaper than replacing the current DPF.

Removal services

Speaking to GW, head of research and development at Klarius Products, Doug Bentley said: “The reality is that the functional part of a DPF is a ceramic block inside a tough metal casing, it is brittle and can be drilled through and/or smashed, so the functional part of the device is removed and the casing is simply bolted back into the exhausts system.

“From the outside it looks like all is well.

“However, removing the filter element not only releases clouds of harmful soot but often the ceramic brick is also a catalytic converter, so harmful exhaust gases can also be released into the air too.

“If a new test can show-up when the DPF is an empty casing, not just missing from the system, then this practise of removal may stop, or reduce, which will be a good thing for the environment, the car’s engine and the customer’s wallet at the pumps.”

38,000 premature deaths

Diesel particulate matter is damaging to the heart and lungs and has been linked by The World Health Organisation to 38,000 premature deaths every year.

In a recent crackdown on test stations that advertise DPF deletion services, the DVSA issued serious warnings for testers and garages offering DPF deletion services.

Speaking earlier this year, MOT product manager at the DVSA, Danny Charles said: “Remember, the consequences of turning a blind eye to a missing diesel particulate filter – or worse, actively taking part in their removal – can be serious for an MOT tester.

“A vehicle that needs a particulate filter and doesn’t have one should fail its MOT.

“If you pass it knowing that it doesn’t have one, you’re harming the environment and committing fraud.”

DPF vehicle data

However, many argue that the DVSA needs to do more to make data readily available for testers.

Commenting on GW recently, technician David said: “DVSA really need to be clear about which vehicles are actually fitted with DPFs to ensure testers are also made properly aware of which vehicles they should be fitted to.

“DVSA have taken a back seat with the VMs and gaining technical information.

“It’s time they put their foot down and got it then pass it onto the test stations that need it to do the job correctly.

“I for one still don’t know which vehicles are supposed to be fitted with a DPF.

“I came across a Transit with no exhaust system on seeing only a tail pipe mounted at the exhaust manifold area, thinking that some clever trader had removed the DPF.

“I failed it, only to find later from Ford that they didn’t fit a DPF to that model of Transit.

“Testers have got the short straw here.”

Do you think more needs to be done to tackle DPF removals? Share your comments below.


  1. I would agree that testers need more exact information.
    When a tester fails a vehicle for this reason they are
    1)Accusing the owner of deliberately breaking the law
    2)Insisting that an expensive replacement is necessary.
    Before doing that exact information is essential.

  2. we as mot stations will have to foot the bill for equipment to check cats and vosa will not give us a price increase our set prices you know this will happen they dont care about the testers/ stations as long as they look good

    • its a joke aircraft spewing out crap hydrogen cars solve this problem but the oil companies wont like it thats why we still have emissions damaging the air

  3. we test to 3.00 or 1.5 % on the later cars on the smoke test which is a fudge because if you look on the vin plate in a little square box will be 0.5. That was the maximum percentage that was allowed on the later cars and all should comfortably be inside this if properly maintained. Cars which have their DPFs removed sometimes creep inside but not often but have no problem with 1.5%. VAG group cars always pass as they don’t rev using a tiny amount of fuel to do nothing even ones with sooty tailpipes…I wonder if something was missing inside a dpf ???

  4. The dpf system is complex and can be simple to understand for someone who is trained . If for some reason the dpf blocks then the route cause of this needs to be fixed before any action is taken on removing the blockage .

    The biggest problem is the main dealers along with Halfords are clueless to this system and have no idea what they are doing.

    Get the problem looked at by a specialist and the truth is you won’t have any problems.

  5. Dint know why they have been so slow at bringing this out
    They have been testing ultra low emition trucks for years with a separate smoke tester !!!

  6. Bringing the smoke level down isn’t going to work it’s NOx emissions that need testing not smoke, if the exhaust system is less restricted and someone has tampered with the internals it would apear to be cleaner due to no soot build up within the CAT or DPF
    the main cars to fail a smoke test are those driven around town all day as the exhaust system blocks up over time.
    And as previously mentioned there are many vehicle manufactures that have fitted a DPF to one particular model and not another.
    Am I right in saying that NOx emissions are tested in Europe?

    • Nox is only produced at high combustion temperatures under heavy load so unless you have a way of replicating that how would you be able to test for nox?

  7. With regards to the statement below.

    “If a new test can show-up when the DPF is an empty casing, not just missing from the system, then this practise of removal may stop, or reduce, which will be a good thing for the environment, the car’s engine and the customer’s wallet at the pumps.”

    Does this person understand what and how a DPF works on a car? Maybe they are getting mixed up with the EGR valve with regards to economy. Also the first time Ive heard someone state that a DPF benefits a cars engine. Really like to here his explanation on that.

    ps. I do not agree with removal of the system myself.

    • Quiet agree Ryan. Lots of smoke and mirrors on this subject with many not really understanding what a dpf actually does, what effect this technology has on a vehicles long term reliability, and thats before the discussion regarding EGRs is dealt with. Where drivers warned of the cost of maintaining this technology when they purchased their vehicle ?

  8. The whole uproar about testing for soot particles is so fatuous.
    Ok Sir just drive for 5 miles at a steady 60 mph and all your troubles will be behind you!!
    In reality, spread your particles over the countryside ,but not on my garage forecourt.
    Have we all given up on reality? The only way forward is to ensure that when produced, the soot must be contained and disposed of in a controlled manner. I look forward to the mandatory introduction of a DPF cleaning and capture system that is recognised as safe and sensible.
    Money Save Service Centre Altrincham.

  9. i agree with Craig who said you would have to test the NOx. all cars with inside of particulate filter missing , would pass a mot test as it stands at the moment ?

  10. Whilst there is a big question mark over DPFs and as this issue attracts more attention so will the science behind it, costs and associated damage and costs. With DPFs being fitted since 2002 there are most likely millions of vehicles with ineffective or removed dpfs ! Why ? because the technology is flawed. Huge repair bills have been generated from this failed technology along with unexpected replacement dpf costs…with most owners never being notified that, A) it might happen & B) how expensive they are.

  11. Sorry but I can’t see simply reducing the smoke limits will make any difference to the problem of removed DPF’s. As someone said above all the time we’re testing VAG group cars that only rev to 2k or so NOTHING is going to fail.
    The only real answer is to produce kit that can test emissions (including NOX) whilst the car is being driven on a reasonable test route. But, for obvious reasons, that’s never going to happen. So all we get is brave talk which, although the intentions are good, isn’t going to change anything.

    • I got a 08 car no dpf but told fine as need 11 cars for dpf apply has passed so far however i got it like this it cost as fortune to replace inc remap. Is that fair. It was probably fine when i got it. An passing smoke test. @-1.0

  12. It’s about time the manufacturers and the dealerships got there arses kicked because neither of them gave out the advice about the problems related to the dpf’s and the cost of replacement ..

  13. This problem it’s going to get worse. The software emissions “Fix” for VAG vehicles increases soot 3 fold. Three times the soot= three times the DPF problems.

  14. Hello. Why the hell they don’t comes with a proper solution of dpf? Why it’s costly to regenerate or fit a new one ? Why they don’t make it easy to replace the filter at low cost ? Is goverment trying to clean the air or cleaning driver’s pockets?

  15. There is only one cure, no Diesel engines. Until someone can produce a cleaner diesel burning engine the problem is not going away. Local running, low mileage vehicles will continue to block the DPF. Regeneration needs to be set to actuate at lower temperature and way before the filter becomes blocked. I carried out a clean on a Suzuki that went over 1000degrees inside the Filter. It got so hot it ignited the pressure sensor rubber pipe. Is there really a solution?

  16. I agree completely with the three comments above, In a nutshell it’s a European directive that had good intentions but ultimately it ended up costing unweary user’s, ( I know because my Daughter has just forked out £1500 for a new DPF on a 2012 Seat!).
    Why not make a filter cartridge that can be exchanged at service time like an Air, Oil,Fuel,Pollen filter is changed?
    Oh yeah, I forgot there’s no profit in that!
    Jaded opinion? yes, I have lost faith in the design resons behind some ‘new’ technology.

  17. Edit, I don’t agree with the comment by Ken, it appeared before my reply
    Diesel can work!!

  18. How can you test for nox since its only produced at very high combustion temperatures under heavy load? How would you be able to replicate that at a testing station? Simple answer is you wouldn’t .

  19. Dpf is Just another motoring con, the connection to lung issues is a tenuous as saying step ladders are responsible for broken necks ,yes if you sit of the back of my exhaust sucking the fumes up then you will die of lung issues otherwise in the real world you will defiantly die at some point in your life from something else and that’s a fact

  20. Well here we go again.More expensive eqipment needed to carry out tests on DPF’S What with all the changes to tester training in recent times dvsa patting theirselves on the back and making a big noise about how good they are at saving money(at everyone elses expence by the way )and yet still nothing has been done about the mot fee ,large outlets we all know who they are are allowed to use mot’s as a loss leader (buy a new tyre get a free mot) with absolute impunity.Does anyone out there have any figures for the number testers who have had enought of all the cr.p and given up testing in the last 2yrs fed up with being the whipping boy for an agency which seems to have completely lost the plot.If you can have afixed price for a test across the the whole country for a truck mot why not for smaller vehicles? Sorry i forgot its dvsa who get paid for that.

  21. my Land rover is 20 years old and i cant se a DPF so where dose that leave me? if the DSVA buy me a new candy that conforms ill be happy I seldom use it and it seems all of these new criteria standards dont see the whole picture…

    • Id imagine this legislation would only apply to vehicles fitted with a DPF from manufacture. No one is saying that all diesels need to be fitted with a DPF only that if fitted they cant be removed or tampered with.
      I personally have always had 4×4’s as we live on a farm but I wouldn’t buy one that has a DPF fitted due to the expense if / when they go wrong.
      Jeeps in particular seem to be quite late in their model years in installing DPF’s. I have a 2008 WK Grand Cherokee with no DPF fitted as standard only a CAT. I wouldn’t have bought it had it had a DPF fitted.

  22. Well lots of comments but everyone driving around the roundabout not knowing where the exit is. Why did consumers buy a car with a DPF fitted? simple, it gave them cheaper road tax, it is fitted with one purpose to reduce the Diesel particulates from everyday use the incentive to the driver or owner was cheaper road tax, there has never been a claim to my knowledge that a DPF had any benefit to the engine or fuel economy, were buyers mislead when buying these cars? probably but i doubt intentionally by a car salesman. While it was a good selling point for the sales person i doubt that they was ever given the true cost of a DPF breakdown as who would buy a car to save £100 or so a year in road tax with the knowledge that 5 to 6 years down the line it would result in a repair bill of an open cheque book? As evidence here, not all mechanics here have a full understanding of the workings of a DPF system, you see many garages regening the DPF but you have to ask why? If the DPF is blocked the most common problem is it is out of DPF fluid, and that brings in a whole new ball game, less than 1% of all garages are licensed to do this job, DPF fluid is one off the most toxic chemicals around transporting the stuff requires hazmat training and licence, yet companies put it in a bottle and slaps a label on the side telling you to avoid contact with skin eye’s and the rest of the garbage that is listed, the truth is YOU REALLY DON’T WANT TO TOUCH THE STUFF. The fact of the matter is this, using a vehicle that is declared to have a DPF fitted and has had it removed the owner is committing fraud as they are benefiting from the rewards of having it with the knowledge it has been removed, and in my opinion any mechanic aiding the removal is of a DPF is adding in a crime also as they are aware of the tax benefit of the system but are making money by working on the removal of the DPF helping the person commit fraud. So glad i don’t have to make these decisions.

  23. I feel good about the fact that both of my diesel cars a 52 reg Citroen Synergie 2.0 hdi 16 valve and a 04 reg 1.4 hdi 16 valve C3 are just old enough to have never been fitted with these dreadful devices, the dpf. What will happen is this the list of vehicles fitted with these brainwash devices will be made known to mot test stations and pre dpf diesel cars will command premium values like a good fifties Buick in downtown Havana.

  24. DPF has nothing to do with CO2 emissions on which VED is based.
    If anything it makes CO2 emission higher

  25. Everything that others have said is true, except no one is telling it like it is.
    The DPF filter is a con!
    It’s supposed to reduce harmful emissions of soot but in reality the emissions it lets out, are worse than a 1950’s tractor.
    The DPF traps the larger soot particles BUT, it lets the microscopic particles through!

    It’s these particles that are now free to float in the air, that cause most lung problems!

    These same micro particles used to cling to the larger/heavier particles & fall to earth.

    It’s also interesting to note, that the scientific study that found these flaws in the DPF system, has mysteriously vanished!!


  26. Where does this leave people who have bought diesel cars with a DPF, second hand, and when it comes to MOT they are told they fail because the DPF has been removed. How were they supposed to know when buying their cars the DPF was taken out and do they have to foot the bill as someone else was doing something illegal?
    Doesn’t seem fair that people pay so much for cars and then pay a large chuck to fit their cars with a flawed system again.

    Is there nothing else to insert other that a DPF? A cheaper work around?

    • I’ve just discovered that dpf on my car has been removed. I was taking out the engine to replace clutch and noticed there was a cut and weld marks on the filter housing. I chased the previous owner and he confirmed it was removed when the car was remapped. I was not informed of this when I brought the car.

  27. A green light for unscrupulous garages to totally rip off the less knowledgable motorist. More unwelcome interference from the EU.

  28. The testing std and policies will change in the future too but testers are the most important piece in the mot testing std. They must be made aware and educated to the extent. They are very knowledgeable in performing their job, after all they represent the Dept of transport too Inc sect of state? Inc physical inspection, times Tester cannot even see the DPF? Fitted or not? Perhaps this subject needs a little more in depth investigation/hope it makes sense?

  29. I had a car with an early model of the DPF (Vauxhall 2006 1.9cdti) and it was beyond rubbish. It used to “Regenerate” every 500 miles and it would use about 30% more fuel.. It used to spit out white smoke all the time.. Had it cleaned, helped for about 2000 miles. Then had it replaced at a cost of 750 quid, again about 2k miles. Absolute crap. Also this EGR component clogged my engine up. Also blanked off. Performance is far better and economy is better. Compared to the pollution the car used to cause, i doubt that its any good for the environment. Luckily i now live in a country where they dont check this kind of stuff.
    Tip by the way. I had it MOT’ed in Northern Ireland at one point, and they dont even check smoke or anything on diesels.. I Doubt they will now either. They pass the car through the MOT station in about 15 min..

  30. Forgot to mention. When i asked how to prevent it, i was told to drive down the motorway doing over 3000 revs.. How bad is that for the environment. Its useless. I can drive 70 miles an hour and do less than 2k revs in 6th gear. Why would i want to do 3000…

  31. I Don’t blame people removing the DPFs, after coughing up for a new one there is a likely chance it will clog up again. Its a con and hitting consumers in the pocket. If your an urban driver then stick with a petrol.

  32. As a member of the public the only way to tackle this is to make the dpf cleaning service cheap as garages can charge what they like. If its an expensive and regular thing. People are going to remove it as soon as its Mot’d. Alot of people have these for school runs and around town.So dpf problems is going to be a regular and expensive thing.


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

Have your say!

0 1

Lost Password

Please enter your username or email address. You will receive a link to create a new password via email.