Information and FAQs

Replacing the diesel particulate filter on your vehicle will not be cheap. On a car a new DPF will cost something around £1000 + vat to replace and for a larger commercial vehicle or HGV, the cost is likely to be over £3000 + vat. Replacement of the DPF should only be needed in the most exceptional of circumstances.

Diesel particulate filters are not so much ‘repaired’ as cleaned. During their everyday operation, DPF’s do not have moving parts, so there is nothing to repair as such.

DPF regeneration is a process where the Diesel Particulate Filter gets rid of the build-up of soot that is the result of the diesel fuel combustion process – it effectively self-cleans. There are three types of DPF regeneration: passive, active, and forced.

The use of Diesel Particulate Filters on vehicles means that the days of dirty black smoke pouring out of a diesel engine’s exhaust should be long gone, and strict emissions regulations require diesel engines to be a lot cleaner.

The diesel particulate filter on a vehicle does not have any moving parts, as a vehicle engine has and as such it doesn’t require servicing as a routine element of prolonging its life, maintaining efficiency. However, if soot builds up in the DPF because the vehicle is primarily used for short journey’s then the DPF is likely to require cleaning (or servicing), or in the worst cases, completely replacing.

The simple answer is that you can drive with the DPF light on, but the car is giving you a warning that cannot be ignored. If the DPF light is on, but the vehicle is running well, the normal advice would be to take the vehicle on an extended run, probably on a motorway, running at around 3000 revs per minute for at least twenty minutes.

Totally replacing a DPF when it is blocked – and the cost that is associated with this – should be a rare occurrence today. There may be circumstances where a Diesel Particulate Filter gets blocked with soot and then is treated with an inappropriate soot cleaning fluid that actually solidifies the built up soot in the filter rather than loosening it.

As a Diesel Particulate Filter removes soot particles from the engine exhaust of a diesel car, so those soot particles build up in the filter over time. As this build-up occurs, sensors in the exhaust will trigger the DPF to ‘burn’ the soot at high temperature and turn it into ash, which is then disposed of.

The answer to this question is that it depends on what method of DPF cleaning is being used. At Darwen Diesels, we offer a 24 hour turnover time for our DPF cleaning service. Each DPF is thoroughly cleaned using our Flash Cleaning Machine which flushes water through the DPF cleaning away soot and ash deposits until it is returned to an almost new state.

The simple answer to this question is that you can clean a DPF filter, but ideally you shouldn’t have to because the car’s DPF filter should be self-cleaning or ‘self-regenerating’ as it burns off soot collected in the filter and turns the soot into ash which is expelled.

In theory, vehicle owners should experience very few problems with the Diesel Particulate Filter, as it should be self-cleaning or ‘self-regenerating’.

There are several reasons why DPF’s get blocked.

The main reason is that the vehicle’s own temperature- based regeneration mechanism hasn’t been initiated. The car’s DPF needs a temperature of around 600c in order to burn off the soot in the DPF and turn it into smaller-particle ash which is more easily expelled from the exhaust.

There are several methods of cleaning Diesel Particulate filters in the market, and they achieve varying degrees of success. Ultrasonic cleaning is available, as is blasting a DPF with compressed air to remove soot. Probably one of the more popular techniques is putting an additive into the diesel fuel tank on a regular basis or spraying a cleaning fluid directly into the Diesel Particulate filter. Both of these techniques will loosen the soot and debris that has collected in the DPF, and once loosened regular exhaust gases will flush soot out of the DPF and clean it.  

The cost of DPF cleaning varies depending on the service that might be chosen. An apparently simple and inexpensive solution such as putting an additive into your diesel fuel tank every other fill up will, over time, become a more expensive solution than you might have anticipated, and there are question marks about how effective some of these fuel additives are in doing a good job of cleaning the DPF. This criticism can probably be levelled at many of the DPF cleaning services that involve the use of a chemical additive injected directly into the DPF or added to the diesel fuel tank.

Since 2009, which was when the Euro 5 emissions standard was introduced, every new diesel engine car has been fitted with a Diesel Particulate Filter (or DPF).  The DPF is self-cleaning and for a number of diesel car owners, the existence of a DPF and what it does, is of no consequence to them.