What is a Diesel Particulate Filter?
Find out more about this important component of diesel vehicles, and why servicing is critical to preserve your vehicle’s performance
The diesel particulate filter or DPF
The diesel particulate filter or DPF collects or traps diesel particulate matter as it travels through the exhaust system. The filter is made up of thin tubes that are capped at one end to only allow the exhaust gases to pass through.
As the particulate matter builds up in the filter, it also increases pressure inside the exhaust system. Once the pressure reaches a certain level, usually around 11 PSI, the engine computer will start a DPF regeneration process.
Fuel burns inside the filter itself, raising the temperature to an extreme degree and burning away the diesel particulate matter.
Regeneration
Regeneration usually occurs when the vehicle is at a constant cruise and the engine speed is near 2500 RPM.
The engine computer causes the fuel injectors to spray additional fuel during the exhaust stroke. This extra fuel raises the temperature inside the DPF, incinerating the diesel particulate matter so that the exhaust gases are able to flow through the walls of the filter again, thus lowering the pressure inside the exhaust system and restoring engine performance.
During regeneration due to the extreme temperatures the cooling fan is turned on by the engine computer and may run even with the vehicle turned off.
If the vehicle is turned off midway through the regeneration cycle, the engine computer will force the cooling fan to keep running to dissipate the high temperatures produced during regeneration.
DPF Diagram
How a DPF is situated in a diesel-powered vehicle’s exhaust system.
DPF Examples
Illustrations of Diesel Particulate Filters
Diesel Particulate Filter
Model of a typical example of a diesel particulate filter, of a type fitted to many diesel vehicles.
Diesel Particulate Filter Cutaway
Cutaway model illustrating the composition of the diesel particulate filter (DPF).
