When you remove a diesel particulate filter (DPF) you essentially not only remove a problem, which may be costing you a fortune, but you remove a blockage in the exhaust system – a blockage which creates additional back pressure and so, once its removed the car has more power and runs better. Removing a Diesel Particulate Filter (DPF) is not just about removing the Diesel particulate filter section or cutting open the DPF Filter itself and removing its insides, it also requires the vehicle ecu computer to have the section which deals with the diesel particulate system deleted, essentially reprogramming the car, and making it forget that it ever had a diesel particulate DPF system fitted!.
Provided the work is carried out correctly, and the DPF program section correctly mapped out from inside the vehicle computer, then running without a Diesel Particulate (DPF) system should be trouble free and the car more reliable, have more power and return a much better MPG but that isn’t where the problems are, its the legalities and the risks, which may essentially end up costing you far more than replacing the DPF.
So far this may seem very tempting, but a problem is looming, and it can be a very serious one, which although unlikely, can leave you open to the risk of a criminal conviction.
Removing a Diesel particulate filter in the UK, and indeed the majority of Europe is illegal, and since 2014, in the UK it has also been an MOT failure, and is an offence under the construction and use regulations, under which the owner may be prosecuted and fined for one or more offences in relation to the modification.
At the time of writing this, the MOT checks are still easily defeated since it forms just a quick visual check for the presence of the DPF canister in place on the exhaust system, and so having the actual filter cut open, modified and re-welded is unlikely to be discovered and fail an MOT – at least until more intrusive tests are introduced to the MOT system, to interrogate the engine computer for the presence of a Diesel particulate filter, a test which will undo the current workaround of removing the DPF insides and then re-welding and refitting the DPF section to the exhaust, to fool the MOT visual check.
However, the legalities and risk posed by illegally removing the diesel particulate filter doesn’t just end at the MOT test. Removing a Diesel Particulate Filter is a vehicle modification, a huge, illegal modification at that, and one that should be declared to a vehicle insurer. However, unlike a legal modification such as a remap or upgraded lights, since removing the DPF in the first place is illegal, its impossible to ever insure a vehicle with the DPF system removed or defeated. So if an owner goes ahead with the removal in the event of a serious accident if the insurance investigator finds that the DPF has been removed and the vehicle contains an illegal modification, then the insurance company has the right to void the cover, leaving the vehicle and driver uninsured and facing prosecution and a potential criminal conviction. In the event that insurance cover is revoked then the insurer may choose to persue the driver privately in order to recover any monies that they have paid out to any third party in relation to losses or injury, or replacement road barriers and street furniture.
Since removing the Particulate filter, also increases the emissions of the vehicle, it may change the VFD band and the annual amount of road tax which is due, which may result in the DVLA deciding to prosecute the owner for fraud or at least chasing them for any back tax payments due.
Removing a Diesel Particulate Filter will cost around £400 – £500, whilst replacing the DPF with an aftermarket system will cost about the same, but will keep you on the right side of the law, and keep your insurance cover intact. Please see our page on Aftermarket Diesel Particulate Systems for more information on replacement DPF systems which cost a fraction of the dealer parts.