A Diesel Particulate Filter (DPF) is a device that is fitted to the exhaust system of diesel cars in order to reduce the amount of harmful soot and particles produced during the combustion process. The DPF captures and removes particle matter (exhaust soot) from diesel exhaust gas. The DPF is a vital component in helping to meet current emissions regulations, and as such, it is an important part of a car’s exhaust system.

The DPF works by filtering out the soot and storing it until the engine reaches a high enough operating temperature to burn the soot, converting it to less polluting ash. This process is called regeneration, and in DPF terms, there is passive and active regeneration. Passive regeneration occurs when the car is running at speed on long motorway journeys, which allows the exhaust temperature to increase to a higher level and cleanly burn off the excess soot in the filter. Active regeneration occurs when the engine management system senses that the DPF is becoming blocked and injects extra fuel into the engine to increase the exhaust temperature and burn off the soot.

It is important to maintain the DPF to ensure it is fully able to regenerate itself when it’s full of soot. If the DPF warning light appears, it is not okay to drive with it on, as it indicates that there is an issue with the DPF system, which can lead to increased emissions and reduce engine performance. Additionally, it can cause the engine to overheat and potentially lead to costly damage.

Some tips to maintain the DPF include making sure the car isnt always running on an empty fuel tank, using the oil recommended by the car’s manufacturer, and ensuring that the car is driven at a constant speed for a good amount of time to allow the DPF to work properly and use the exhaust heat to turn the soot to ash. A DPF can last up to around 100,000 miles if maintained properly. It is illegal to drive a car that was designed to have a DPF without one fitted, and removing a DPF can also invalidate the car insurance policy.