What is a DPF?
A diesel particulate filter (DPF) is a device which sits within a vehicle’s exhaust system and is designed to “capture” soot/diesel particles to reduce harmful emissions into our towns and cities.
It became legal for vehicle manufacturers to fit DPFs to all vehicles when “Euro 5” emissions standards came into force in 2009, although some VMs did fit them prior to 2009.
DPFs are intended to self-clean, through a process called “regeneration”. This happens under certain driving conditions and the particles are emitted, leaving only a small ash residue. Sensors in the DPF unit communicate with the vehicle’s central computer (ECU) to determine when to clean/regenerate the DPF.
Why do they block?
Firstly, they shouldn't block. A blocked DPF is usually a symptom of another problem with the engine, causing either premature blockage or failing to perform a DPF regeneration.