https://mattersoftesting.blog.gov.uk/diesel-particulate-filters-protecting-the-environment-and-the-mots-integrity/

Diesel particulate filters: protecting the environment and the MOT’s integrity

smokey diesel car exhaust

Since February 2014, when an MOT tester inspects a diesel vehicle’s exhaust system they have to check if there’s a diesel particulate filter. Diesel particulate filters are important in maintaining acceptable levels of air quality.

How do diesel particulate filters work?

Diesel particulate filters trap particulate matter, like soot, from exhaust gases. They’ve been used for more than 20 years and have been fitted on all diesel vehicles since 2013, as part of the Euro 5 emissions standard.

If they’re not filtered out, diesel particulates pollute our air and can damage our health, so these filters are vital in keeping our air clean and protecting us from pollution.

Removing diesel particulate filters

There are 2 main reasons that some people might want to remove a vehicle’s diesel particulate filter.

1. Performance

Some garages claim removing a vehicle’s diesel particulate filter will improve its performance and make it more economical to run.

2. Cost

Some garages also claim that removing the particulate filter is cheaper than replacing an old blocked up filter with a new one.

However, it’s illegal to drive a vehicle that’s been modified in that way.

MOT ‘friendly’ removals

Our enforcement team recently investigated 2 linked companies, who were offering to remove diesel particulate filters from vehicles - describing their services as being “MOT friendly” and “hard to notice”.

Both companies regularly recommended each other on social media, but claimed to our investigators they had no official relationship, despite sharing the same address, staff and directors!

As a result of our investigation, we found the directors of the diesel particulate filter removal company were authorised testers. These MOT testers were banned from conducting MOT tests for 2 years and the owner of the MOT station was banned for 28 days.

Serious consequences for testers and garages

The bans give a clear message about the importance of maintaining the integrity of the MOT. 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.

Fines for drivers

For drivers, the penalty for driving a vehicle with the diesel particulate filter removed, are fines of up to £1,000 for a car or £2,500 for a light goods vehicle.   

Undeclared illegal modifications (like removing a diesel particulate filter) could also invalidate a vehicle’s insurance, so it’s not just garages who could face serious consequences.

Maintaining integrity

During 2016 to 2017, we issued 761 warnings or disqualifications to MOT garages or testers who carried out improper tests, putting all road users at risk. That’s a tiny proportion of the 60,000 or more MOT testers in Britain.

We know the vast majority of you wouldn’t ever consider making modifications to cars that make them unsafe – and illegal – to drive. It goes against everything the MOT stands for, and as MOT testers, you’re at the forefront of making sure the MOT’s integrity is maintained.

109 comments

  1. Comment by nige posted on

    DPF like you say if you cant see you cant fail.

  2. Comment by Steve posted on

    I think that a official online forum for MOT testers would be really useful. Each Matters of Testing blog post has so many comments, its hard to read them all. A forum would be a better format for people to share their ideas/thoughts etc.

  3. Comment by DAVID posted on

    WHAT HAS A DPF GOT TO DO WITH ROAD SAFETY, ONCE AGAIN THE TESTER IS POLICING ENVIRONMENTAL ISSUES, SAME AS NUMBER PLATES WE CHECK THEM TO MAKE SURE THEY CAN BE SEEN ON POLICE CAMERAS, LETS JUST GET BACK TO MAKING SURE A CAR IS SAFE TO DRIVE ON THE ROAD, BE SEEN CAN GO ROUND CORNERS AND STOP! WHY AM I BEEN USED BY THE ENVIRONMENTAL AGENCY FREE OF CHARGE

  4. Comment by Graham posted on

    Could you please clarify what you mean by 'tyre pressure monitoring system lamp illuminated indicating a FAULT' Do you mean a fault with the system eg sensor down, or just a fault with tyre pressures? Ive just had a kia sportage in with a tpms light on constantly which means tyre pressure low, but if the light was flashing it indicates a fault with the system eg, sensor. So are we meant to fail if there is a light on full stop, or only when the light indicates there is a fault with the system? Thanks

    • Replies to Graham>

      Comment by Julia (DVSA) posted on

      Hi Graham

      The MOT Inspection Manual is very clear on this. The 'reason for rejection' is for “A tyre pressure monitoring system warning lamp indicates a system malfunction”. Clearly, if the lamp is on because there is a low tyre pressure, then the TPMS is working as intended and there is no malfunction.

      • Replies to Julia (DVSA)>

        Comment by mark posted on

        it doesnt say that

      • Replies to Julia (DVSA)>

        Comment by mark posted on

        the defects wording is incorrect

      • Replies to Julia (DVSA)>

        Comment by Graham posted on

        Okay thanks for clearing that up. However, in my opinion it is not very clear.
        I have come across many testers who fail because tpms light is on due to low tyre pressure. May i suggest adding a line to the information column stating that if the light is on due to a low tyre pressure then its not a fail. Thanks

  5. Comment by castrolrob posted on

    theres nothing stopping any one welding a crack/cutting it open to clean etc.not every system has pipes and very few are visible,in common with petrol cats they are moving them closer and closer to the manifold to improve warm up times.in short a visible exam of any sort is a waste of time.if you work for(for instance)in the below mentioned merc dealer you would know what should and shouldn't be there but as a tester you have to prove its been removed/interfered with.you cant.the general garages out there have even less hope,a functionality test is all that's left as a viable option,cut off date,pass/fail said function after said date.simples.no rqmnt to examine,it just has to work,as I mentioned in a previous post after 5yrs of this we have yet to be notified of which vehicles even had to be fitted with them.the repute of the testing scheme starts with the organisations administering it,get your act together.all this article will do is encourage testers to fail em(cos that's the impression it gives)despite the fact that in practice we are NOT allowed to.misleading at best.

    • Replies to castrolrob>

      Comment by Julia (DVSA) posted on

      Hi Rob
      You are correct that it’s not always possible to spot if a DPF is not present. The article has two points to draw VTS’ attention to the consequences of getting involved in DPF removal and to remind people of the current test standards. These will be changing from next May and more detail on this will follow. We will be taking a robust line where DPFs appear to have been opened and re-welded but you are quite right – even then not all will be visible.

      • Replies to Julia (DVSA)>

        Comment by mike posted on

        an easy way to check if the DPF is complete is to check the temperature gradient along its length.but of course only if it can be seen.

  6. Comment by Derek posted on

    I read with interest the comments relating to proposed changes to checking the DPF in the spring of next year.

    My own position on this would be as follows.

    DPF canisters are of a stainless steel external construction any post manufacture welding would only be needed to carry out illegal modifications to the unit.

    I have seen post manufacture welding to these canisters which in recent times has been almost undetectable as they are becoming more sophisticated in there deception. Removing the canisters cutting along existing weld lines and re-welding professionally.

    It is also very easy for these unscrupulous individuals to hide the modified DPF canisters underneath factory fitted under trays. Notably, Mercedes under trays virtually cover the whole of the front section of the exhaust system.

    It would seem to me that to help MOT testers in being able to check effectively we could either

    1. Allow for partial removal of under trays where necessary to allow access for a remote camera facility etc.

    2. Software Interface via EOPD 16 pin socket to check functionality of the DPF unit pressure differential sensors etc. for vehicle within EURO 5 category.

    3. A better emissions tester for EURO 5 category vehicles.

    While on the above subject we could help testers in the future by making it mandatory to use exhaust extraction.

    I know that many may comment about the possible additional costs associate with my suggestions, but maybe we should not be allowed to discount the price or offer incentives in anyway for a mandatory inspection.

    Regards.

    • Replies to Derek>

      Comment by Graham posted on

      Dpf could be cut open to jet wash out, or removed blocked internals and replace with new internals by a re manufacturing company. Yeah sure its quite likley internals have been removed but unless we can see inside we cant tell. DVSA will need to be very clear about 'obviously modified'. Once again the blame will be on tester if one is failed, yet customer appeals and wins. My position would be, unless you are 100% sure fail, if you are 99% sure, pass with an advisory. At the end of the day, the most important thing to us testers is keeping our licenses / clean. As long as the customer has been advised that we think it has been messed with its up to them

    • Replies to Derek>

      Comment by Julia (DVSA) posted on

      Hi Derek

      Thanks for these suggestions. We recognise these difficulties – particularly with components not being accessible. We will make some changes from May next year, and are continuing to work with DfT on what longer term options may be.

  7. Comment by Linda posted on

    The dvsa don't seem to care about the health of its testers . It wont be long before someone sues them for exposing testers to harmful smoke and excessive noise. Duty of care ? Perhaps they have

  8. Comment by Paul Stember posted on

    Keep sending us feedback

    One of the other useful pieces of feedback we’ve had is that it would be helpful to let testers add technical information that they know. We’ll need to give this some thought to determine how this could work, but the principle sounds great, and it’s something we’ll look into.
    mattersoftesting.blog.gov.uk/making-vehicle-technical-information-available/

    DVSA make it hard by not providing examples for testers, FEEDBACK lets have a new feature'Testers Tech' or 'Forum Tech', whatever you want to call it added to Matters of Testing consisting of Short videos and pictures of known Failures and Official responses to forums as reference to known failures.

  9. Comment by B.W. posted on

    I think it is about time we had a test that actually tested a diesel for pollution. The test we carry out at the moment is a joke...I've only had a handful of diesels fail, all filled the bay with smoke in a couple of minutes, no need for diesel tester. A lot of modern diesel cars don't even register a reading, others pass easily, but when they drive off up the road, have a smoke haze behind them.

    • Replies to B.W.>

      Comment by Stephen posted on

      Hi, B,W
      Like you I'm fed up testing diesels, sit outside engine on fast idle for a good 10/15mins for it to pass or NO ACCELERATION DETECTED, GRRR.
      Then on the other scale we fill the workshop up with BLACK SMOKE, About time they stopped this test BAD FOR OUR HEALTH

  10. Comment by tim posted on

    Dvsa need to do secret shopper exercises to MOT stations also offering re-mapping as a high percentage offer dpf removal

    • Replies to tim>

      Comment by Julia (DVSA) posted on

      Hi Tim

      Thanks for the suggestion. We are already upping our enforcement in this area - and building our intelligence.

  11. Comment by Lee posted on

    My Nissan X Trail just pre dated having a PDF filter. Having read about the problems people on a Facebook blog have with their later X Trails fitted with a PDF makes me think I'll just keep my old car going or if Ido have to change it I'll buy a petrol engined car.

  12. Comment by T J Nutt posted on

    Please can you tell me who will be responsible when every one has a car that drives its self, and passing a driving test is no longer a mandatory requirement .Will it be that bunch of hypocrites that think you can exterminate the internal combustion engine . replacing every thing with some form of electric motive device controlled from afar. A real reduction in emissions can be achieved by giving tax reductions to people that live in closer proximity to their work, and impose mandatory limits on power out puts for all cars.produced after a fixed date .evolution will then bring about a more efficient use of the planets resources .In the same way that cheap finance has made a far greater contributions to road safety than the, MOT ever did. I guess its a Funny old World

  13. Comment by Anthony posted on

    The advise from my last VOSA (DVSA) training was if a DPF Filter is fitted but welded Pass and Advise!!!
    The need to stop the removal of DPF Filters needs to be stepped up, most taxis have no DPF'S

    • Replies to Anthony>

      Comment by Linda (DVSA) posted on

      Hi Anthony, thanks for your comment.

      We agree this is an area of concern and are looking at making some changes to the Tester’s Manual from next spring - one change will allow a failure for equipment such as this ‘obviously modified’.

      More details will follow as we move towards making this and other changes to the manual.

  14. Comment by alan dawson posted on

    Particulate trap removal is only one cause of pollution through owner actions. I have personally come across several cars where the E.G.R. valve has been blocked off, and an aftermarket tuning company, has remapped the engine ecu to not put the E.M.L. light on as a result of this. Should this not also be looked into, as this practice must drastically, increase the amount of Nox gasses emited by the car?

  15. Comment by darren croft posted on

    so a guy comes in with a leaking dpf at the weld seams and its repaired with fresh weld . month later it goes for mot and fails on being modified the customer not being happy contacts dvsa a meeting arranged and the filter cut open and there it is still intact . my quiestion is who side is dvsa going to be on .

  16. Comment by Ashley farnden posted on

    My new Ford focus when in clean mode puts out more black soot and rubbish than my 20 year old diesel Peugeot has ever done. Not to mention reliability issues with stopping exhaust gases from properly leaving an engine costing more in the long run!

  17. Comment by Amaan posted on

    Say you have an old car that has no dpf when it left the factory. Can i still be fined

    • Replies to Amaan>

      Comment by Paul posted on

      No you cant

    • Replies to Amaan>

      Comment by Lloyd posted on

      Fined for what? If it never had one in the first place, there is no requirement for it to have one

  18. Comment by A. JONES. posted on

    DPF removal is widespread problem and also includes cat removal on petrol vehicles always has been and always will be with companies openly offering a removal service . When a vehicle is presented for test we are told the customer must always be given benefit of the doubt so the argument for poor welding around a dpf is a joke . I have reported several re mapping centres for dpf removal and nothing has ever been done the DVSA is only interested in punishing MOT testers and stations and not catching the actual people removing the dpf's and cat's . On another note will Mot testers and vehicle technicians be allowed to sue the manufactures now that it has been proved that diesel fumes are extremely harmful to health?

  19. Comment by Andy Olds posted on

    After the government told everyone get a diesel its cleaner and cheaper, people went out and bought one. Manufactuters then fitted dpf filters, which are very expensive to replace, they do block and the advice on a burn cycle on a vw golf is to drive it in such a manner which is faster than our countrys national speed limit. All a bit of a con to generate money for the government and car manufacturers. A lot of garages do remove them as its cheaper to do that then replace, reprogram and unblock a few month later.

  20. Comment by Lonewolf posted on

    So you give us a small amount of relevant information, required since 2013 but in use for over 20 years. MOT failure when removed where fitted as standard so when do we get the relevant data on what vehicles over 4 years old had DPFs fitted?

    • Replies to Lonewolf>

      Comment by Julia (DVSA) posted on

      Hello

      Thanks for your comment – DVSA will look at the data we receive from DVLA to see if there is a simple way of presenting this information to Testers via Vehicle Technical Data either by using year of manufacture or CO2 emissions data.

  21. Comment by andrew posted on

    There also seems to be a lot of d-cat petrol vehicle driving about on the road, either fitting cat for mot and swapping over after the test or the testing station turning a blind eye

  22. Comment by Riley posted on

    Not good if you own a car like a tdi golf and most of the time your on small journeys and low revs, it always clogs your dpf and egr and your warranty company calls it wear and tear, id rather remove then to get a new one fitted and spend a fortune, along with the egr, blank and remove. is the best thing for these cars, saves a lot more money

  23. Comment by Michael Richards posted on

    If MOT testers are letting cars pass with the DPF removed then they probably letting other defects through for a backhander. Any MOT tester caught doing this should not be allowed to test cars again, a 2 year ban is not enough. This article also highlights the fact that a DPF will fail if a diesel car is only driven on short journeys. A DPF needs to reach operating temperature to be effective which is only acheived on long journeys, if the DPF starts to clog up then the car will go in to a regen mode that's is achieved by over fuelling.

  24. Comment by Simon green posted on

    How come nobody mentions the carcinogens that are emitted when dpfs regenerate reducing our air quality and causing cancer ?

    • Replies to Simon green>

      Comment by Simon Blue posted on

      You just did!!

  25. Comment by Patz posted on

    Worst thing ever invented as they are to expensive to replace .
    30,000 ml upwards before a clean or replacement ????.
    A part on your car is that is not up for the job same with egr valves.
    Lasting performance from car making engineers will work.
    car showrooms sales don't tell customers any of this ?????????.
    Think of an old person wanting to get the best mpg, buys a diesel,
    Drives slow for best mpg around town or short journeys to the shops what ever BANG they you go another blocked filter £££££££££££££££££.
    DPF should be fully guaranteed problem solved.

  26. Comment by Johnson posted on

    Easy to spot a dpf removed deisel, they sound like a turbine when accelerating & chuck out huge amounts of soot under even light acceleration. They have a high pitched dump valve sound like a high performance turbo petrol vehicle.
    They shouldn't be on the road

    • Replies to Johnson>

      Comment by Rob Deacon posted on

      No not always, I had the DPF removed on my last car and there time as 0 soot or smoke. If the car puts out black smoke or soot then it’s been mapped badly or had the pump turned up too much.

    • Replies to Johnson>

      Comment by Bob posted on

      Not necessarily. Cannot rely on that to tell if it has dpf or not. Noise depends on length of exhaust , amount of silencers, air intake system etc. Smoke could be due to a defect with something else or defective dpf not necessarily because it's been removed . A lot of assumption on your part

    • Replies to Johnson>

      Comment by david posted on

      my focus has its dpf and still sounds like that

  27. Comment by Mark Jones posted on

    We need a better system from the manufacturers, the problems people are having with the emissions systems on vehicles is creating the market for this fraudulent work. It's just as bad in the heavy vehicle sector.
    Unfortunately legislation is moving quicker than the manufacturers can, most people would confirm, modern vehicles are very reliable except for the emissions systems.

  28. Comment by Cecil Colhoun posted on

    I hear from various people that in N. Ireland where MOT is only entrusted to government test centres that they no longer do emission tests on diesel en gines. This (I'm told) is as a result of serious damage caused by revving engines to an unacceptable level. So a lot of people have DPF removed as they see no issue with it.

  29. Comment by Ian Coleman posted on

    I agree with the comments about MOT stations being struck off for life when fraudulent test are done, its there in black and white and you can phone for help if you have difficulty in working anything out?

    • Replies to Ian Coleman>

      Comment by Paul posted on

      Unless enforcement is carried out on the likes of every fiat dobolo taxi on all taxi ranks etc the Dpf rules are a waste of time and most tests a carried out by councils.

  30. Comment by Les fenn posted on

    The penalty for incorrectly conducting an MOT should carry a life ban. How can DPF removal be proved by a tester during a test. It would appear that the DVSA are now putting further pressure on testers when perhaps it would be better to educate the public about the legalities of removing an anti pollutant from their vehicles. And should all those garages offering the removal service be stopped from trading whether a testing station or not perhaps then this illegal act would be eradicated.

  31. Comment by Craig posted on

    Too little too late springs to mind but there's always a legal process to go through so that could be he reason for the delay.
    Also it is worth noting that the equipment required to test for Nox and other gases that would tell you if a DPF had been removed is really really expensive, who pays that bill?
    DVSA? No, they're self funding.
    The M.O.T test stations would have to and that would increase the test price, also if it wasn't mandatory the garages that didn't purchase the equipment can undercut all those that did.
    There's no quick or easy fix to any of this.

  32. Comment by Steve .J posted on

    Just a thought on the ( senario ) . I'm just imagineing a vehicle presented for test and it appears to have had the DPF internally removed ( let's suggest the casing has evidence of fresh welding around its perimeter) . What if the owner / presenter suggests the internally have been removed for chemical cleaning and then refined , as a tester we wouldn't be able to prove if it has or hasn't been reffited. Therefore would it be correct or incorrect to give the "benefit of doubt " to the presenter?

    • Replies to Steve .J>

      Comment by Julia (DVSA) posted on

      Hi Steve

      Current MOT rules state that ‘on all compression ignition vehicles - check for the presence of a diesel particulate filter’. And they can only be failed where
      ‘a diesel particulate filter missing where one was fitted as standard’.

      So in this scenario the vehicle will pass the test. However, we agree this is an area of concern. We are looking at making some changes to the Tester’s Manual from next year. One change will allow a failure for equipment such as this ‘obviously modified’. More details will follow as we move towards making this and other changes to the manual.

      • Replies to Julia (DVSA)>

        Comment by Graham posted on

        Obviously modified still wont cut it. Just because there is a welded plate on a dpf dosnt mean it has been obviously modified, it could have been repaired, cleaned etc. You can only be sure it has been obviously modified if it has obviously been removed so its the same as the old fail.

  33. Comment by Guy Gibson posted on

    Mot diesel emission tests need to measure gases and particulates...not opacity!!

    If the dpf canister is present but has poor welding around a the end cap seam, you can suspect someone has tampered with it. I am seeing quite a few of these. Would DVSA SUPPORT me if I failed a vehicle with this condition.? Highly unlikely, as you can not prove the inner filter has been removed with any part of the test. The emission test has to change to trap these.

    • Replies to Guy Gibson>

      Comment by Nkaka posted on

      Remember , you can not fail what you can not see. This is a grey area that the powers that be seem inadequate in finding a workable solution or way forward.

      • Replies to Nkaka>

        Comment by Linda (DVSA) posted on

        We agree this is an area of concern. We're looking at making some changes to the tester’s manual from next year. One change will allow a failure for equipment such as this ‘obviously modified’. More details will follow as we move towards making this and other changes to the manual.

  34. Comment by Fred King posted on

    If a vehicle has had the particulate section of the exhaust removed and the particulate filter ''broken out' and then refitted, how is a tester supposed to be able to see and fail a vehicle, with what from visual inspection appears to be a 'normal system' ?

    P.S. I have worked in the motor trade for 52 years many of them in PSV garages had have consumed vast amounts of diesel smoke, I don't know of anyone that has died from a direct consequence of breathing in diesel smoke. I doubt the authenticity of source of these 'reports'

    • Replies to Fred King>

      Comment by peter jeffery posted on

      Hi Fred
      Nice to see you still have an interest in the vehicle test world.
      It would seem to me that DVSA have a bit of double standards here anyway
      as when ever i present a goods vehicle for test the emisions are never tested
      only by eye !
      I also now have 43 years working with diesel vehicles and i am still here no one realy remembers the old smokey diesels in truck from the seventies.

  35. Comment by mercedes posted on

    its comman up here in central scotland but if it looks like a dpf filter you have to pass it even though you can see the welds on it and you know its been removed but my xray vision is on the fritz but vosa has a up grade in the pipe line for this ha ha

  36. Comment by Cj posted on

  37. Comment by Cj posted on

    2 year ban and 28 days what kind of deterrent it that !

  38. Comment by Colin Greenhough posted on

    I worked on the old Gardner diesels in the 1970s . We all worked in a smoke filled workshop and guess what we are all still alive and kicking . You do good ers should remember that we all rely on the Diesel engine . From the the field to the plate all our food is produced using Diesel engines . All you are doing is succeeding in making food more expensive and less plentiful. How are we going to feed 9 billion people by the middle of this century

    • Replies to Colin Greenhough>

      Comment by Anthony posted on

      Colin, I too worked with trucks having Gardener engines. In the winter when the vehicles were parked in the workshop, we started them up to warm them up & you could not see a hand in front if you. I am still here.

      • Replies to Anthony>

        Comment by Gavin Robinson posted on

        The soot particals where much larger from older diesels because of the much lower injection pressures. There are hundreds of companies shouting from the rooftops about removing dpfs that are working or failed. Would not be hard to clamp down on them for a start.

      • Replies to Anthony>

        Comment by Guy Gibson posted on

        However there were fewer vehicles around, air quality was better, so the percentage of particulates per cubic meter of air was smaller in comparison to what is being breathed in now.

        Please explain why there was no visible Nox smog over cities then and there is now. (Brown haze).
        Unfortunately I think all MOT testers should have a class legal case against VW and the like for breathing in excess Nox gases and particulates over and above what we expected.

      • Replies to Anthony>

        Comment by peter lancaster posted on

        Yeah,me too, white smoke Lol.

  39. Comment by Brian posted on

    If Diesel fumes are so harmful shouldn't there be an healthier way for MOT testers to check the emission instead of having to bend in front of a running exhaust to place the probe in then rev it in an enclosed place to get a reading up to 8 times a day .
    Or am I missing something on an health and safety issue if the fumes cause so many health and deaths problems

    • Replies to Brian>

      Comment by oily al posted on

      Very good point the other guys in the workshop get upset as i leave car/van to warm up for oil temp reading

  40. Comment by brian posted on

    diesel testing is a joke its not policed much only if a vehicle is leaving plumes of black smoke behind it then local plod might get involved and lorry testing is visual only and they are worse vehicles for pollution at the end of the day there is not a clean vehicle on the planet its an excuse to rob the poor motorist of more money it has nothing to do with safety and that is what a mot test is designed for enough ranting for now

  41. Comment by Simon posted on

    Given the importance, set against the potential for confusion with type of engine, year of registration. transfers of private plates etc, why not insert a flag on the system, perhaps under VSI, to notify tester that a vehicle just entered for test should have a DPF fitted. I recognise that there are plenty of other standards which are applicable based on date of first registration, but these are usually easier to determine if they are/should be standard equipment; DPF is less so. I note also that it is the case that a tester will only be disciplined if they 'knowingly' passed a vehicle where the DPF had been removed. If it is a reasonably skilled bodge such that the canister is still present, then on present test methods they would have no way of knowing.

    • Replies to Simon>

      Comment by Julia (DVSA) posted on

      Hi Simon

      Thanks for your comment. We will look at the data we receive from DVLA to see if there is a simple way of presenting this information to Testers via Vehicle Technical Data either by using year of manufacture or CO2 emissions data.

  42. Comment by J Bennett posted on

    dpf's are a short term fix anyhow as every regen burns al the sox and nox out and pollutes the enviroment anyhow so its totally hypercritical,, and what about all the MOT / garages that illegally flush them out and wash all the harmful deposits down the drain,,,, the motor industry is again used as a test bench,,, dont see Ships, Trains, Planes, Gensets etc etc etc having DPFs

  43. Comment by Otis posted on

    Whilst the DpF is part of the test it is impossible for testers to challenge if it has been tampered with or not if the case welding is good enough. Not having X ray vison and the MOI is merely " is it there" really is not good enough if this testable item is so important.

  44. Comment by Andrew highs posted on

    In fact they do help with fuel economy if they are gutted and Ecu re written as when in reg mode the Ecu pulses the injector 8times per stroke to regenerate the dpf hence your burning more fuel and money so it good for the government if your buying fuel and not saving it

  45. Comment by SIMON HANLEY posted on

    How can you tell if a dpf has been gutted the reason for rejection is A catalytic converter or particulate filter missing where one was fitted as standard .so my interpretation of this is that if a straight through pipe is fitted yes it fails but how do we know if its been gutted and even if it was gutted what is the failure criteria as its not missing it just not working as its been gutted.

  46. Comment by Jon posted on

    I do not under stand why the smoke test is still the same dpf or not
    For trucks there is a separate smoke tester for dpf / low emission vehicle and a lot tighter limits
    Most cars we test do not even register when smoke tested so I can not see how the test can find a dpf car that is either smashed out or faulty

  47. Comment by castrol rob posted on

    when this was first dropped on us I expressed concerns via comp 1 that it was utterly unenforceable given that we were not even going to be informed which cars had them and which didn't let alone the visibility problems on most vehicles,i pointed out that unless a guy in our garage removed it in front of me I would have to pass and advise.in the event of me failing it and a later appeal dvsa would then have to pass and advise because they wouldn't have seen it being removed!the only reply I got was along the lines of dvsa hoping that the manufacturers would be providing the relevant information in something like the old emissions standards book.comp 1 message number was 095177706 and said reply was furnished by a rob evans.is this guidance still current given it is dated 9/2/14 and I aint seen it yet?because if not then all you are doing is beating us poor testers over the head with another pointless(unless disciplined!)pass and advise exercise

  48. Comment by James Shand posted on

    While i agree with most of the above it should be noted that any garage can undertake the removal of such components , that are not testing stations and seem to be untouchable for doing so . The rest of the industry needs to be regulated. ...... That was the short version.

  49. Comment by martin mcdonald posted on

    yes its all very well to check if the dpf is there but what do you do when its been opened up then welded shut but still passes the emission test, who knows what's gone on inside

    • Replies to martin mcdonald>

      Comment by Julia (DVSA) posted on

      Hi Martin

      We agree this is an area of concern. We are looking at making some changes to the Tester’s Manual from next year. One change will allow a failure for equipment such as this ‘obviously modified’. More details will follow as we move towards making this and other changes to the manual.

  50. Comment by P GOODSPEED posted on

    It's huge business in Portsmouth area, loads of small garages removing & remapping! IT'S NOT POLICED ! So they will just carry on polluting us all.
    Emission machines need updating fast to enable proper test to be carried out. Preach what you teach DVSA.

  51. Comment by MR G J hardington posted on

    Its really good to know that these filters are in use .

    I have a 66 plate diesel so I have one fitted.

    Thanks for the imformation

  52. Comment by geraint posted on

    Still a poor inspection process by dvsa. If its such an important part then test it correctly and fully. Not yeah looks like its there then theres no chance of a vehicle passing without a dpf. Problem solved

    • Replies to geraint>

      Comment by gav posted on

      I completely agree had a conversation with dvsa about a Volvo that had dpf cut out but canister was still there. They told me to pass and advise.

      • Replies to gav>

        Comment by Andy Constantinou posted on

        If it looks like its there and passes the emission test it has to pass.We can't dismantle to check so pass and advuse that it looks tampered with. Cover your backside.

        • Replies to Andy Constantinou>

          Comment by castrol rob posted on

          even if its obviously been cut out/removed you would still have to pass and advise.you have to be able to PROVE that it was there,you have to be able to PROVE it was fitted as standard and is now missing.when you have a piece of pipe welded into an exhaust how do you tell if its a prior repair(allowed)or a cat/dpf that's been removed?you cant.i see a fair few vans etc that have pipe work welded in the area I would expect to see a dpf/cat largely due to the nocturnal activities of people who travel a lot and sleep in caravans,that isn't the owners fault,he knows nowt till he gets up the following morning to an exhaust that's been snipped in half,i know folks that have had this happen so repeatedly that they refuse to refit a cat as theres no point,itll just get stolen again.

      • Replies to gav>

        Comment by george weatheritt posted on

        I've seen several cut and shut dpf's on vehicle's I've tested an been unable to do anything about it . the owners know its been tapered with ,add the word's modified to the list of failures ,sorted .

        • Replies to george weatheritt>

          Comment by Linda (DVSA) posted on

          Hi George, thanks for your comment. We agree this is an area of concern and are looking at making some changes to the Tester’s Manual from next year. One change will allow a failure for equipment such as this ‘obviously modified’. More details will follow as we move towards making this and other changes to the manual.

    • Replies to geraint>

      Comment by Dan posted on

      I have an 07 diesel car only a 1.3cdti but I’ve certainly polluted the world enough even with the Dpf in as it’s currently sitting at 185k & you know what the best of all the tax is only £30 a year so I’m happy to pay if I can pollute away 😂

  53. Comment by Matt Firth posted on

    Planning to abolish diesel passenger/private vehicles with intention to hybrid, more information please

  54. Comment by mark nixon posted on

    the sooner you bring out a valid way of testing for dpf removal, the better, for all of us!!

  55. Comment by alfonso piccoli posted on

    i totally agree with it but 2 year ban is not enough for fraudulent behaviour

    • Replies to alfonso piccoli>

      Comment by james woodcock posted on

      any mot station found to be doing fraudulent tests should be struck off for life .

      • Replies to james woodcock>

        Comment by Dave h posted on

        The station only receiving a 28 day ban is total joke.

      • Replies to james woodcock>

        Comment by John Reynolds posted on

    • Replies to alfonso piccoli>

      Comment by Andrew higgs posted on

      You can't test them as they don't work until wide open throttle under load that's when nox EMMISIONS are produced

    • Replies to alfonso piccoli>

      Comment by Chris posted on

      28 days for the garage owners & 2 years for the tester seems a little unfair, both are equally corrupt so should both have the same punishment.

  56. Comment by Peter Gleeson posted on

    Where do u stand if the dpf has been cut open and welded back up , as you can't tell if has been removed different to if it is just missing

    • Replies to Peter Gleeson>

      Comment by Julia (DVSA) posted on

      Hi Peter

      We agree this is an area of concern. We are looking at making some changes to the Tester’s Manual from next year. One change will allow a failure for equipment such as this - ‘obviously modified’. More details will follow as we move towards making this and other changes to the manual.

      • Replies to Julia (DVSA)>

        Comment by Dave posted on

        I have never removed a DPF but I have had them cut open and cleaned therefore have signs of welding but are still there , so failing them for that worries me.

    • Replies to Peter Gleeson>

      Comment by Mike Smith posted on

      Pass and Advise. Its all i ever do if the vehicle passes the emmisions test. Its about time the dvsa brings in opacity readings that dpf equipped cars will pass under. I think a limit of 0.25 would completely suffice.