What are the symptoms of a blocked DPF?

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. However, conditions need to be right for the soot to be burnt off, which is a temperature of around 600°C which is normally only achieved by running a car for a reasonably sustained period at around 3000 revs per minute. This temperature will not be achieved if the vehicle is only driven for short local journey’s, however, and it is this driving pattern which can cause Diesel Particulate Filters to get blocked, and require a forced regeneration.

The first that you might know that you have a problem with you DPF is when the DPF warning light comes on.  If you were to refer to the car’s handbook, it is likely to state that you will need to take the car on an extended run of over 20 minutes at speeds over 60 miles an hour to build up sufficient heat to ‘burn off’ the soot. Without this, soot will continue to build up, affecting the efficiency of the engine, which will cause more warning lights to go off. Within a short period of time, the DPF will be beyond ‘active’ regeneration where the vehicle burns off the soot, and is likely to require the forced ‘reverse flush’ regeneration that we provide at Darwen Diesels that returns the DPF to an almost new state.