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Posted by Elizabeth Davis on

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 Diesel Particulate Filter however it is only now that it is being checked and enforced as part of the UK’s annual vehicle inspection (MOT). Similar Laws exist across most of Europe and in the U.S Emissions Laws are often even stricter.

So, if you vehicle is presented for an MOT and the inspector believes that the DPF system has been removed, reprogrammed or otherwise bypassed or tampered with then your vehicle will fail the MOT test until a time when the inspector is assured that 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, its removal may go unobserved.

However, its only a matter of time, before the MOT in the UK becomes as strict as those in Germany, Spain and many other European countries. Devices do already exist which plug into the vehicles diagnostic (OBD) port and read information directly 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, resulting in an MOT failure, and this technology could be introduced into the 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 between £1500 and £3000 to refit, should new MOT rules require 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 five years have removed or bypassed their troublesome Diesel particulate filter systems, and are now faced with with having to pay anywhere between £1000 and £3000 for the entire particulate filter system to be re-fitted and the ECU /DME reprogrammed back to its original factory state, it will also be potentially bad news to buyers of second hand diesel vehicles, who will now have to take additional care that the “bargain” which they are buying, is not advertised so cheaply, because their owner removed the Particulate Filter and now doesn’t want the huge four figure bill to replace it!.

It is unfortunate that both the UK Government and VOSA have adopted this knee jerk stance towards enforcing Diesel Particulate Filters, 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.

In short, if the Diesel Particulate Filter system worked correctly and reliably in the first place, then there would be no reason for car owners to remove them in the first place!. With the cost of a simple Diesel Particulate Filter clean, averaging around £400, and replacement particulate filter costing a large chunk of the vehicles’ value it is quite understandable that the temptation to remove them exists. Especially as the DPF removal cost is only around the cost of having it cleaned, but giving a more permanent solution.

A quick search on Google for “DPF Failure” or “DPF Problems” brings a huge number of results, all largely from owners’ forums and in relation to various problems with the Diesel Particulate Filters on their vehicles, and often these forum threads usually end with the inevitable solution which requires expensive dealer rectification. 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 2009, and all fitted with DPF systems (Many BMW’s using the 3.0 Litre Diesel engine have had a diesel particulate filter fitted since 2004)

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 law should also be levied on the Manufacturers and guarantee’s should be offered on these systems against failure for a minimum of at least Five to Seven Years.

At the end of he day, if the Manufacturers don’t have enough faith in their DPF products to back them with at least a full Five Year Guarantee, then there shouldn’t be a compulsory requirement for them to be fitted to every vehicle on the road.

I wonder what would happen if brakes were failing as often as often as DPF Failures were being reported?, there would be a huge outcry, and so why should attitudes be any different to widespread reports of DPF problems?, after all the Environmental groups tell us that DPF systems are instrumental to health and lives, and so the DPF system should be extremely reliable, just as reliable as other safety systems within the vehicle.

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 an 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 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 for no other reason than for one of its components to service itself in a world of dwindling oil resources and congested roads, was 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. 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 of £1000’s in dealer servicing if it is ignored, is this point really that far fetched?.

So currently, the best advice I can give, is that until the DPF situation improves, a potential car buyer should avoid buying any diesel car which has a DPF fitted, if they are only expected to make short journeys and have very little motorway use. 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.

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