What is a DPF?

A diesel particulate filter (or DPF) is a filter that captures and stores exhaust soot in order to reduce emissions from diesel cars. Modern diesel cars are all fitted with DPFs as standard, however they do run the risk of getting clogged if a car’s used mainly for short journeys. Having a DPF fitted on to a diesel car is standard procedure and the Euro 5 exhaust emissions legislation in 2009 to help lower emissions made DPFs mandatory. A DPF check has been part of the MOT test since February 2014, garages and test stations are required to check for the DPF in the inspection of the exhaust system. The vehicle will automatically be failed if the filter had been fitted as standard but is found to be no longer present. DPFs work by trapping the soot produced by engines and stopping it from entering the atmosphere. But because they only have a finite capacity, the trapped soot periodically has to be emptied or ‘burned off’ to regenerate the DPF. To maintain a healthy DPF it’s important to let it regenerate. This happens when the car is running at speed on long journeys, this allows the exhaust temperature to increase to a high level and burn off the excess soot in the filter.

Why remove them?

Some drivers think that by removing their DPF, they are removing their problem. This is not the case, not only is it illegal but they are also removing a device that is designed to protect the environment. The act of removing the DPF is not against the law, however it is illegal to drive a car that has had it removed. Any garages that encourage a DPF removal are

What can be done alternatively?

Diesel engines are designed for longer journeys, so the diesel particulate filter can burn off its soot deposits. So identifying what kind of driver you are before purchasing a car is important to reduce the risk of blockages and clogging. If a driver expects most of their driving to be city based, a petrol engine is advised. If an instance occurs where a DPF does become blocked, it’s important to know that replacement is not the only option. Diesel particulate filters are very expensive. A new one from a car manufacturer can cost between £1000- £3500, which can potentially wipe any savings associated with driving a diesel. If you think your DPF might be blocked, put in your postcode above and find your nearest dealer for a diagnosis.