Diesel Particulate Filters – What do they do and what are the problems?
Diesel Particulate Filters (DPFs for short, also called FAPs) are devices fitted to diesel engine vehicles to reduce the sooty particles that diesel engines produce. These can penetrate deep into the lungs and are seen as being responsible for an increase in heart and lung problems.
The Diesel Particulate Filter has a honeycombed interior, similar to a catalytic converter, which is made of silicon carbide. This is inside the steel surround that you can see.
This honeycombed centre is designed to trap the particles of soot which have not been burned off or cleared by the additive.
Some Diesel Particulate filters use an additive which enables them to burn off the soot particles, and some are fitted closer to the engine which means that the exhaust gasses are hot enough to burn off the carbon soot particles.
When the filter is full and no more soot particles can be trapped the DPF needs to undergo a regeneration process, which converts the soot into a small amount of ash. There are two types or regeneration process which take place in ordinary usage.
The most frequent kind of regeneration, passive regeneration should automatically take place when the vehicle is driven at higher revs for a longer period (for example if being used on a motorway for a reasonable distance). This enables the exhaust temperature to reach a level which can burn off the soot for a sustained period. There are however many vehicles which do not undergo these kind of trips frequently enough for this to happen as often as is needed.
If the vehicle doesn’t make these journeys often enough in regular use it is advisable to deliberately drive the vehicle in this way to actively try to start a regeneration and clear the warning light.
Driving at a speed of at least 40mph for 10 to 20 minutes is usually enough to start a regeneration if the filter is not too blocked.
Sometimes the filter will not be given the chance to undergo either of these regeneration processes, and the filter will become too blocked for a regeneration to take place. At this point the vehicle will need to undergo some type of professional service.
The only solutions at this stage which will leave the vehicle in it’s proper state, are to replace the filter (usually £1,500 or more) or to use a professional cleaning service which DMS Garage Service can provide. Tel: 0115 9264566 for a quote today.