DPF Diesel Particulate Filter

DPF (Diesel Particulate Filter) also known as FAP on some French vehicles, is a device fitted to the exhaust system of modern diesel vehicles to reduce emissions and meet European emission standards. It does this by trapping Soot (Particulate Matter – PM) from the exhaust gasses while letting the gasses flow through the system.

As with any type of filter a Particulate Filter needs to be cleaned regularly to function properly. With DPF’s this is done by a process known as Regeneration which involves a combination of a Catalyst function in the system and burning the soot to gas at a very high temperature leaving behind an Ash residue within the DPF. Regeneration should be an automatic process taking place in the normal use of your vehicle, you may have noticed this in the form of a blast of white smoke form the exhaust on occasions.

DPFs have been in common use in passenger cars and light commercials from around 2003 in preparation for Euro 4 regs (2005), with Peugeot, Renault and BMW being early takers. Euro 5 (2009) made it compulsory for diesel cars and light commercials to have a DPF fitted and Euro 6 2014 will tighten this up further.


DPF Diesel Particulate Filter

If regeneration doesn’t function properly it leads to a build up of soot affecting performance and fuel economy, left unattended this will result in a Blocked DPF which can ultimately cause very expensive damage to other engine components. A blocked DPF is also potentially dangerous as it can cause overheating in the exhaust system and cause a fire risk. To prevent this damage most newer vehicles will go into “Limp Home” safety mode at this stage, meaning the vehicle will have minimum power barely sufficient to crawl home. For regeneration to take place it requires the vehicle to be driven regularly at some speed on open roads e.g. motorway driving, typically driving at around 2500 RPM for approx 30mins at least once a month, this will keep things working. However, many diesel vehicles are used primarily in urban areas or on short stop start journeys e.g. local deliveries, taxi’s, school runs etc and many have auto gearbox, so the vehicle does not get the chance to heat up sufficiently and is unable to carry out a full regeneration process.

Even if the regeneration functions as it should, over time the Ash Residue will build up in the DPF and have the same affect ultimately resulting in a blocked DPF. For this reason a DPF is classified as a Serviceable Item by the vehicle manufacturers like brake pads or air filters etc and not covered under warranty. DPF systems therefore need to be maintained properly.


Our fully trained technicians will remove the exhaust system from your vehicle and inspect. The internals of the DPF section of the exhaust will be carefully removed and the caucus left in place. The exhaust will be refitted to the vehicle and will visually remain unmodified. This removes the need for bypass pipes etc. Once the DPF has physically been removed from the car, we will take a read from the Engine Control Unit using specialist equipment. We will modify the data within the ECU to prevent any warning lights in the future.

You can be assured, after our modified software is installed, your car will no longer attempt to regenerate the DPF, display any warning lights or go in to limp mode.

Removing the DPF from your vehicle is not only a cost effective solution but it also boasts the following advantages:

  • Increased Performance
  • Increased Efficiency (MPG)
  • Less Turbo Lag
  • Reduced Maintenance Costs

Please note that we offer DPF solutions for off-road usage only.  It is not illegal to remove a DPF filter from your vehicle.  It is an offence under the Road Vehicles Regulations (regulation 61a(3) 1, to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet.  Removal of a DPF will almost invariably contravene these requirements.

From February 2014, the inspection of the exhaust system carried out during the MOT test will include a visual check for the presence of a DPF.  A missing DPF (where one was fitted when the vehicle was built) will result in an MOT failure.

Therefore, by fitting a bypass pipe you will find that your vehicle fails an MOT test.  Other methods, such as removing the internal filter, will be visually standard and will enable you to reinstall a filter at a later date should you wish to.  Please note this will contravene MOT regulations by completing this.

The potential penalties for failing to comply with regulation 61a are fines of up to £1,000 for a car, or £2,500 for a light goods vehicle.

There is no doubt that DPF removal is now considered illegal by the Government, despite no actual law being passed to make it such!

mobileECOtuning can also fully refurbish your DPF all in house using our state of the art DPF ash removal machine. We have a 100% success rate with this machinery in removing the Ash content from your DPF. Replacement is also an option but we will not fit aftermarket DPF systems due to reliability.