As with any filter, they ‘filter’ or trap particles, in this case harmful diesel exhaust soot particles, so they have to be emptied regularly to maintain performance. The DPF needs to be cleaned regularly, through a process called regeneration, either active, passive or forced regeneration, the accumulated soot is burnt off at high temperature (around 600°c) to leave only a residue of ash, effectively renewing or regenerating the filter, ready to take on more pollution from the engine.

Why does my Diesel Particulate Filter (DPF) block?

Every vehicle type & engine combination can have differing reasons as to why the filter blocks. The rate of particulates generated by the engine, the quality of the fuel, quality of the or oil, driving style, even the location of the DPF in the exhaust system can all contribute to the filter blocking or not regenerating fully.

• Use low ash engine oil: Not using the correct oil specified for your engine can significantly add to the soot build-up in the DPF.
• 100% Diesel Bio Fuel: Using these Bio Fuels can also contribute to extra soot build up loading in your DPF as the Bio Fuel may not burn as ‘clean’ (produce more particulates) as your regular Diesel fuel.
• City Cycle driving: We don't all use our cars in the same way, if you only use your car around town you may experience a faster build-up of soot in your DPF as the regeneration process may not complete in short city or around town driving.
• Temperature: The DPF relies on temperature to carry out a filter regeneration, at around 600c, so a lot of short trips, low speed driving will not provide the exhaust system with a high enough temperature to begin or complete a regeneration, so the filter can block up faster.
• High Kilometre vehicles: As these vehicles with DPF systems age they will start to show that filter regeneration is harder to complete. Like any part on the car they do wear out and can no longer be repaired.