DPF Problems

DPF Problems

How to prevent and cure most DPF Problems on modern diesel cars.

A quick search on Google for DPF Failure or DPF Problems returns a huge number of results, all largely from owners’ forums, motoring organisations and car magazines and all in relation to various problems with the Particulate Filters fitted to Diesel vehicles with many of them requiring expensive dealer rectification or worse still, a complete replacement.

This problem is very widespread, and is not just limited to one or two makes of vehicle, it encompasses all vehicles sold in the UK since 2008 / 2009, (Some larger engine and 4×4 cars had DPF’s from 2004) and all fitted with DPF systems, no one vehicle is largely immune from the reliability issues.

Since March 16th 2014, it has become illegal to remove or delete a DPF (Diesel Particulate Filter) unit on any vehicle in the UK, or at least it would be more accurate to state that it has always been illegal to remove or circumvent the factory fitted particulate filter however it is only now that it is actually being checked and enforced as part of the UK’s annual vehicle inspection on cars over three years old.  Some countries in Europe already have stiffer penalties in place, and carry out far more detailed checks, and have done for a  few years.

Since 2018 the UK MOT has also become more stricter, requiring the vehicle to now pass the smoke test level to which it was originally certified too. This makes the already illegal practice of removing the DPF and even defeating the EGR Valve even more detectable.

So, if you vehicle is presented for an MOT / Annual Inspection and the inspector believes that the diesel particulate system has been removed, reprogrammed or otherwise bypassed then your vehicle will fail the MOT test until a time when the factory standard DPF is back in place.

So far, this MOT legislation involves only a visual check by the MOT inspector to ensure that a factory fitted DPF is still in place on vehicles which had them fitted at the factory, so for those who have had their DPF filters removed, hollowed out, and then resealed and refitted *may* have a stay of execution, in that with the (empty) DPF can still in its rightful place, the removal of the filter honeycomb inside may go unobserved.

However, its only a matter of time, before the MOT in the UK becomes as strict as those in Germany and other European countries. Devices do exist which plug into the vehicles diagnostic (OBD) port and read information from the ECU.

Using one of these tools in the UK as part of the MOT test, could easily detect the absence of the DPF innards, and also the fact that the ECU has been reprogrammed to bypass its DPF Regeneration program, resulting in an MOT failure, and this technology, which is already available in Europe could be introduced into the UK MOT test at any time in the future.

Therefore if you still have the intention of bypassing a vehicle DPF in this manner, then I would advise that you perhaps think again, as a new DPF can cost anything upto £3000 to refit, should new MOT rules force you to do so.

The news in relation to the new MOT legislation will probably be both unwelcome and come as quite a shock to many drivers, who, over the last seven years have removed or bypassed their troublesome DPF systems, and are now faced with with having to pay anywhere between £1000 and £3000 for the DPF system to be re-fitted and the ECU set back to its factory default or face MOT Failures or even possible prosecution in the future.

It will also be potentially bad news to buyers of second hand diesel vehicles, who will have to take care that the bargain which they are buying, is not being sold so cheaply, because the previous owner had removed the DPF previously and is selling their car cheaply in order to cut their losses and passing on the problem!.

It is unfortunate that both the Government and VOSA have adopted this knee jerk stance towards enforcing DPFs, because the removal of such systems have generally only been undertaken by vehicle owners as a last resort, simply because they have read horror stories that DPF’s are proving to be less than reliable and that many other owners have been faced with prematurely large repair bills to fix or replace DPF systems on vehicle of relatively low mileage.

It would have been far better for the Government to tackle the problem with the manufacturers rather than penalising the owners with this MOT based legislation. If DPF’s are fitted to vehicles and have to remain in place by law, then an equal level of protection should also be levied on the Manufacturers and guarantee’s should be offered on these systems against failure for a reasonable period of time.

This point isn’t reinventing the wheel, since in parts of the United States, Emissions levels in some States are far more strict that in the UK & Europe, however there is also a good degree of protection afforded to the consumer, as all emissions related components have to carry, by law a full 80,000 mile / 8 year guarantee, and so if any of the many ‘bolted on’ emissions control equipment fails within this period, American customers can claim a full no quibble replacement at the cost of the manufacturer, and rightly so.

At the end of he day, if the Manufacturers don’t have enough faith in their DPF products to back them with at least the same level of Guarantee as exists in the United States, then there shouldn’t be a compulsory requirement for them to be fitted to every vehicle on the road, until this agreement has been reached.

At least one well known car manufacturer, The VAG Group, have issued a DPF bulletin that says that if it is believed that the Customers’ driving style has contributed to any failure of the DPF system, then it will not even consider replacement under the usual vehicle warranty period.

This could potentially leave the owner with a bill of £2000 for a car which is still under warranty and has only covered a low mileage, if it is decided that driving style contributed to its demise. Perhaps its unfair to give the manufacturer sole control over the decision making process in relation to reaching such a conclusion, since they clearly benefit from ruling in their own favour!.

It would be far better for the Government to tackle the growing number of DPF longevity issues, rather than prosecuting the motorist, whose only crime is to remove a part, which, (given the number of issues found from any random internet search), seems to be proving to be not fit for purpose.

There is also the question of just how ‘green’ the DPF is in the first place. Yes, it is undeniable that the DPF system does filter out soot and particles which can allegedly be hazardous to health in urban areas of high pollution.

However on the flip side, for the DPF Filter to regenerate itself when it becomes blocked, requires the car to be driven on a fairly long journey at continuous motorway speeds. So you would have to consider, how, taking a car on a non purposeful journey on a routine basis for no other reason than for one of its components to service itself in a world of dwindling oil resources and already congested roads, is good for the Environment ?.

No doubt that we will soon see a time, when diesel car owners all ceremoniously take to the roads at the weekend for a long motorway drive, just so that the “green” devices on their cars can service and reset themselves, and that would be a ludicrous scenario in a world which constantly lectures us against making needless journeys or excessive vehicle use!.

However given the current instances of Yellow DPF warning lights advising the motorist to make such a journey in their vehicle soon or face a repair bill running into thousands if it is ignored, is my point really that far fetched?.

So currently, the best advice I can give, is that until the DPF reliability situation improves, a potential car buyer should avoid buying any modern diesel car which has a DPF fitted, especially if they don’t do regular motorway trips and high annual mileages.

Unfortunately, with the new legislation now in force, it is no longer possible to buy a modern diesel car with an advance intention of removing the DPF filter or to program it out, as this will be detected upon the next MOT, and may also leave you uninsured or open to prosecution in the event of an accident.

9 Responses to DPF Problems

  1. Nathan Fox says:

    I was very interested to read the comments from admin concerning the relevance of the distance between the DPF and the engine. When JLR introduced the EU6b Ingenium engine to the Jaguar XE 163 HP saloon in 2015 it was able to fit a close-coupled catalyst/particulate filter canister and stick with extended service intervals (24 months/21,000 miles). However, when the same engine was migrated to the Discovery Sport and Evoque JLR was forced to adopt a different exhaust architecture featuring a remote DPF and combined SCR unit called the SCRF. This design has been a disaster for owners due to a combination of low heat and complex NOx reduction chemistry which prevents passive regeneration from occurring. The technical explanation has never been countered by JLR but, because the fault is systemic and affects every 2.0L diesel produced since 2015, the manufacturer continues to blame drivers for any problems, insisting that they are using the wrong “driving style”. Full details of the technical challenges that JLR now admits it failed to overcome are contained in a 20-page explanatory guide.

    16MY-19MY Discovery Sport, Evoque or Jaguar E-Pace SUV owners finding themselves wrestling with big bills and stubborn dealers over this problem should consider contacting the automotive barrister at Stormcatcher. https://stormcatcher.co.uk/resources/land-rover-dpf-issues-oil-dilution/

  2. admin says:

    Hi Peter

    Like i’ve said previously, I don’t trust dealers to spend lots of time fault finding, often for them its much easier and quicker to just replace entire parts, until the problem goes away, or seems to have gone away. I suspect replacing the short motor and DPF didn’t solve the original problem and so the newly fitted DPF has also now blocked. Of course, they will happily take your money to replace the same parts again, but in another few years will you be back to the same point you are at now?.

    There is also the issue with the location of the DPF, on newer cars manufacturers have figured out that putting the DPF close to the Engine, enables the exhaust gas to be hotter, which along with the heat from the engine itself, allows the DPF to passively regenerate during normal running, this means that the soot load is slowly burned off during normal driving, and so the need for the ECU to carry out a regeneration (and inject diesel into the catalyst) is reduced, as the soot loading is kept below normal levels through normal use. However on older cars, the DPF was located further back on the Exhaust and and so passive regeneration simply didn’t occur, which in turn meant that the System regeneration’s (Active regeneration) had to take place every few hundred Miles. If the DPF on your car is located farther back from the engine, then simply the problem is never really going to go away, all you can do is to keep on top of it once its replaced, by following the advice given on my first reply.

    In relation to the current problem, the only replacement i’ve been able to find is in Germany, and they work on an exchange basis, i.e you buy the part at the full price, fit it and then send your removed one back to them within a few weeks, and they refund part of the price. The replacement DPF can be found here, obviously ask your garage to double check part numbers to make sure that it is the same as yours before making a purchase.

  3. Simon says:

    Hi does the Ford Focus 59 plate zetec s 1.8 tdci have a dpf on them

    • admin says:

      Hi Simon

      Ford began rolling them out into some models in 2008, but didn’t fit them to all cars until late 2010. Go to the Ford ETIS website – http://www.etis.ford.com/, select “Vehicle” from the top menu options and then enter in your VIN details. This will list all of the Factory options for your car. You are looking for something in the list which indicates the presence of a DPF, “Stage IV + DPF Emissions” would be one example which Ford use in the options list to indicate that a DPF is fitted. If there is no mention of a DPF, then its safe to assume that yours is one of the 2008 – 2010 models which left the production line without one (Quite a few did, so the odds are quite good!)

  4. Peter says:

    Hello again and thank you for such a comprehensive answer which is very much appreciated.

    I have tried replying a number of times but when hitting the submit button the page showed an error so I thought I’d try again.

    No luch last Friday afternoon at the FAP/EGR specialist in France. In fact he didn’t want to clean anything and beligerantly insisted that if the oil level was rising he would need to test the cyclinder compression and that the piston rings/bores were at fault.

    I’ve looked through all the Toyota paperwork again and at the end of October the fault code was for a blocked DPF and Toyota tried a forced regen but clearly that didn’t work. There have been various recalls and in July 2013 as confirmed by phone this morning by the UK supplying Toyota dealer a new engine block and DPF were fitted and in 2015 the intercooler/vacuum pump were replaced and the ECU reprogrammed.

    Whilst on the phone to Toyota I explained that the main concern was the oil level rising with diesel mixed in and the chap explained that if the DPF is blocked then exhaust mixed with diesel will be entering the sump diluting the engine oil. However reading extensively through some threads on the Toyota owners club the comments from a Toyota technician state that in all his experience the DPF is never at fault and they invariably replace the short engine with various tests being carried out to diagnose other faults and in some cases the injectors need replacing. My short motor and DPF have not even covered 40000 miles.

    So a forced regen hasn’t worked at Toyota and maybe the DPF is blocked and that is the only fault code that I seen apart from on 3 different occasions ‘engine oil level excessive’. Or maybe it isn’t any of those things. Maybe it’s the injectors or maybe it needs another ‘short’ engine?

    My gut feel is to change the DPF at a local garage but they called to say they couldn’t find one in stock (apart from Toyota who won’t supply for obvious commercial reasons).

    If you do know where to find one in The UK that would be great and of course it could be an aftermarket one if necessary.

    again thank you.

  5. admin says:

    Hi Peter

    Sorry to hear of your DPF and Emissions system problems. I agree, that leaving out any indication of either the DPF regeneration process occuring, or an early warning in relation to it becoming blocked, is a bad design, and a flaw but you would be shocked at how many manufactuers are still leaving out these vital indicators, even on new cars.

    Often when the Engine Management Light / Check Engine Light (Spanner Icon) illuminates the damage has been done, or at least its going to cost the customer a lot of money, to rectify. As you no doubt already know, the raised oil level is caused by diesel from failed or aborted regeneration attempts seeping back into the sump oil instead of being burned off in the regeneration completing. This is bad news, especially on a turbo diesel as it can led to premature engine wear and turbo failure. Ironically the fuel contamination of raw diesel diluting the engine oil, can increase the soot emissions from the engine, causing the DPF to block faster, resulting in the need to Regenerate more frequently, and also the additional soot could play a part in the problem with the EGR, although proving it is going to be impossible, I do think that it has certainly contributed.

    I suspect that there is more than one problem happening here, or possibly one main problem which has then led to a chain reaction, which has now given you two or three additional shadows to chase. I’m not an expert but I do think that the EGR blocking is because of the added diesel dilution in the oil, so hopefully once the DPF issue is resolved and diesel stops finding its way into the oil, then this will not occur again.

    The first, main problem is to find out why the DPF Blocked on the first occasion and why the Regenerations have been aborted enough times to raise the oil, to potentially damaging levels. The most obvious cause of this is repeated short journeys, and on a diesel these are considered to be of 15 miles or less, or any occasion where the Engine doesn’t reach normal operating temperature.

    Another cause of Regeneration problems are failed components, sometimes even components which may immediately not have any connection with the Emissions system. Things to check are EGR Valve (which you now already know to be faulty), Glowplugs, Coolant Temperature Sensor and the Sensors which measure the back pressure at either side of the DPF Canister (measuring pressure on the inlet and outlet ports on the DPF and comparing the difference is how the Engine Management system calculates the soot level), so even a faulty sensor can produce incorrect readings, causing the regeneration process to malfunction and these sensors do fail, frequently in some cases!.

    I would hope that the dealer had properly scanned the ECU for Diagnostic Fault Codes which may lead to other failures elsewhere, but personally i’d be getting an independent garage to do this for me, in order to satisfy myself that something else hasn’t been overlooked!. I have heard many times of owners, spending many thousands replacing DPF’s and EGR’s on more than one occasion only to find a faulty glowplug costing 30 Euro’s was the cause of the original failure, and obviously if that isn’t fixed first, then new expensive DPF components are just going to eventually fail also. Having the error codes read via the OBDII socket is easy and straightforward and shouldn’t cost very much as most Workshops will have access to a code reader, it doesnt have to be the dealer.

    DPF’s can be cleaned, and there is a company in the UK called Ceramex who use a similar method, although this is generally reserved for DPF’s which become blocked with Ash, having reached the end of their service life with over 100K miles on them. What you are describing sounds like a “Terraclean” type process which cleans the engine and its components of carbon. Although these have quite positive results, I cannot say with any certainty how effective it would be at unclogging the DPF and EGR Valve, personally I think I would be looking at removing the EGR Valve and having it physically cleaned, I have done some of these myself in the past, using Oven Cleaner and a lot of sweat, followed by a soaking in brake cleaner!. EGR’s are more complex these days, and so certainly don’t go soaking anything Electrical in liquid cleaner!, however it does describe how blocked EGR valves can become.

    Given that the Cleaning process is reasonably cheap (compared to the alternative), then you have nothing to lose by trying it, however I cannot offer you any guarantees as to which of these problems it will cure, if any.

    I can however, offer you some tips on how to prevent the DPF blocking again, the first is to just use the car for long journeys and avoid short trips where the Engine doesn’t get to normal operating temperatures. Also try to keep the revs upto 2800 rpm for 10 minutes at least once every 200 miles by selecting a lower gear than normal, this will raise the Exhaust Gas, Coolant and Oil temperatures, and encourage a regeneration to take place.

    Look out for signs that a regeneration is taking place, before stopping the engine after a journey, these include the Radiator Fans running, or being able to smell a sight burning smell or feel heat from under the car when opening the door. I know its a stupid thing to have to do, open your door before turning off the engine in order to try and find signs of a regeneration occuring, but sadly in the absence of an indicator light, it is all that we can do. If you can avoid turning off the engine mid regeneration cycle, then you will avoid raising the oil level.

    Change the oil every 7k – 8k miles religiously, and ensure that whoever changes the oil uses the correct low SAPS oil for the car. Check the oil level every week and if you see the level rising, then make a point of taking the car on a journey as soon as possible, keeping the car above 50mph and the revs above 2800 rpm for at least 20 minutes to make the engine work hard and get the exhaust gases nice and hot, this will ensure that if you have an aborted regeneration attempt recently, that it will restart and complete during the 20 minute drive.

    I don’t know how easy it is to obtain premium diesel locally depending on whether you are in a Town or Village, but if it is available then try to use it, at least every other fill, but ideally every fill if possible. Its more expensive to buy, but in the long run it will save you the expense of having to replace components like the EGR and DPF, so in the long run you will save money, not to mention the hassle of having your car off the road.

    I doubt that the amount of work required is as extensive or expensive as the dealer makes out, I think they are needlessly ramping up the bill, or perhaps just replacing random components in the hope that they hit the bullseye. I suspect the DPF needs cleaning and possibly the EGR needs to either be removed and cleaned, or replaced, possibly by a second hand one from Ebay or a Salvage yard.

    For the physical DPF clean, I would consider http://www.ceramex.com/about-us/ – although a UK company they do state that they have Agents in France, and they are something of experts when it comes to DPF cleaning. I believe that they actually remove the DPF and clean it off the vehicle, which of course removes any risk of the contaminants moving from the DPF to somewhere else in the engine and causing a different set of problems.

    Finally, one other thing you can try is an additive. Normally I wouldn’t recommend additives as there is far too much snake oil on the market, however I have had some positive results myself in the early stages of testing this, to the point where it may be worth considering, given the little outlay. Here is the link (They will post to France), although you may also be able to buy it locally.

  6. Peter says:

    Hello there. Firstly thank you for this site and taking the time to create it. Having read through it is indeed very worrying as last year I bought a 2010 Toyota Urban Cruiser d4d 4wd and have had nothing but problems with it relating i believe to the DPF / anti pollution hardware. Unfortunately the car doesn’t have a simple regeneration warning light either indicting problem with the DPF or more importantly to tell you a regeneration is taking place. Basically the ‘spanner’ warning light is all you have and that appeared after about 4 weeks so I had it serviced at a quick fit type place and thought nothing else about it. That was September 17. About 3 weeks later I filled up the car and some warning lights came on and the vehicle went into limp mode. I drove straight to a Toyota dealer and they told me that according to their diagnostic the oil level was too high. So I returned back to the garage who had carried out the service and subsequently accused them of putting too much oil in the car. Which I now know wasn’t the case. On their diagnostic it also stated that there was an issue with the DPF so they carried out another full service and ‘cleaned’ the DPF. I know them there and they always seem a professional bunch. They had to get the codes cancelled by Toyota. Again 3 weeks later the dreaded spanner light came on again. This time I went back to Toyota and the fault codes were oil level too high and a forced regeneration was needed. They did that and I paid around 200 pounds but they didn’t even change the oil and after talking to a mechanic friend he told me to do an engine flush and oil change. Into late October now. A few weeks later same again. Left car with Totota for almost a month to look at and I don’t even believe they did anything at all with the car in that time except to present me with a quote for over 3000 euros (I’m in France) to replace the FAP , the EGR valve and it’s cooler and they state that if that doesn’t do the job it could be a problem with the injectors! So they basically even Toyota don’t know. I did an oil /filter change yesterday and the spanner light has disappeared. For now. So at my wits end but my question to you is that you suggest a cleaning service for the FAP (which I somehow do not think is faulty because according to Toyota when they checked on the historical data my car had a new engine and DPF at 29000 miles and it has only 68000 on the clock so the FAP has ‘only’ 40000 miles) at around 250-400 pounds but what is it and where? Here I’m booked in Friday morning to see a diesel specialist who have a machine that can supposedly clean the EPR / FAP / Injectors etc. using hydrogen. It costs from around 65-150 euros and I feel at this stage before replacing anything that it might be worth a go? Are you able to advise? Thank you

  7. John Ellis says:

    It’s not the manufacturer that’s at fault, it’s the dealers who sell diesel cars to people who only potter around town, then wonder why their DPF isn’t regenerating.

    • admin says:

      Sorry John but I disagree, Manufacturers should be designing cars for use in an international market with an ever changing road and population traffic infrastructure, whether a car is used in the traffic laden, roadwork strewn motorways of the UK, the open Autobahns of Germany or somewhere with no motorways like the Isle Of Man, anything fitted to those cars should be adaptable and therefore compatible with those different and in some cases, ever changing environments. Besides, no two people have exactly the same lifestyle or driving requirements and let’s face it, in the very long history of car manufacturing this is the first time, that car dealers are expected to ask questions on their customers’ driving lifestyle in order to assess whether the car is suitable for them, and whilst you may think that this is a step forward, I see making cars less flexible as being far more restrictive for the consumer.

      Even if a Diesel car is suitable for a customer now, what happens if after one or two years, the car buyer changes their Job, move house, has kids etc and their lifestyle or Job location changes, which in turn changes their driving pattern?, should they effectively have to change their car because their driving requirements change?, what happens if the car is on a PCP deal or Finance?. Equally some car leasing deals are ludicrous, and you can find some quite well known companies still offering diesel cars with 5k or 6k mile per year allowances!, why are the manufacturers not stamping on this practice?, most of the larger leasing companies are buying direct, yet it seems fully acceptable with the manufacturers for them to offer low mileage lease terms which would take the car outside of all of the recommendations given by their own dealer network or in their own handbooks!.

      There are also plenty of DPF related problems mentioned on forums from people driving 15k or 20k miles a year, it is not exclusively short journeys that can cause expensive failures and nobody is immune from the potential expense, in fact one of the most popular devices fitted to HGV’s are Adblue defeat devices, and these are vehicles which are in use every day, and up and down the motorway, but they are still riddled with problems relating to their Emissions system. Then there are the numerous issues caused by Back Pressure Sensors and Temperature Sensors failing on DPF equipped cars and these are components which are not directly affected by annual mileage or driving style, yet they do fail and in frighteningly high numbers.

      You mention that you do not feel that it is the Car Manufacturers are not at fault, yet many of them are still not fitting any kind of dpf regenerating indicators to dashboards. Some kind of indication that a regeneration was underway would avoid the driver unknowingly switching off the engine in the middle of a regeneration, a practice which in a lot of cases can cause diesel to leak into the sump, diluting the oil and raising the oil level, eventually risking an engine runaway. Any device which has potential to dump diesel into the sump oil through a side effect of its “normal” operation, reducing its engine oil lubrication qualities and in turn risking damage to the delicate turbo bearings and other parts of the engine should not be fitted to cars!. You have to examine, why the inclusion of such an indicator, which at production level would probably cost the manufacturers less than a few £ is still not fitted in order to prevent potential damage to a device costing £1000 – £2000! several years after DPF fitment became mandatory.

      However you try to dress it up, the DPF was a flawed, rushed out technology, designed to get new cars onto the market whilst meeting an increasingly restrictive set of parameters, and these are problems which still haunt owners even today. The fact that the majority of car manufacturers will not even cover the DPF within their new car warranties, speaks volumes about the level of confidence they have in these devices, and you can generally reach a conclusion about its reliability from that fact alone.

      Interestingly, Particulate Filters are going to be fitted to all new cars fitted with Petrol engines and some Petrol Powered Hybrids, no doubt creating a whole new set of problems, and also making them unsuitable for short journeys. In fact very soon it will be difficult to find a car which is suitable for City use!.

      Finally, whatever you feel about the role of the DPF, independent research carried out by EMPA and recently reported in Science Daily found some modern Direct Injection Petrol Cars to create far more damaging particulates than pre-DPF diesel engines, one part of the report also found a new EU6 petrol to be more damaging to health than an older EU5 Diesel. Food for thought in these days of Anti-Diesel press hysteria, I wouldn’t be at all surprised to see Petrol Cars appear next in the tax cross hairs. The fact that particulate filters are going to be fitted to petrol engines shortly, adds some credibility to the linked report.

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