Diesel Particulate Filters

As their name suggests, Diesel Particulate Filters clean the particulate matter (soot) from exhaust gasses by passing them through a filter that traps the particles.

How they work

  • To maintain engine performance, DPF systems must be cleaned at regular intervals to remove the soot collected.  This is known as regeneration.
  • To burn this soot, additional fuel is injected to raise the DPF temperature to around 600 degrees Celsius. 
  • The vehicle must typically be driven for a certain distance or time, at a defined minimum speed (usually about 80km/h) while this is happening. However, low speed and stop-start driving can prevent the initiation or completion of the regeneration process. 
  • If this requirement is ignored, vehicle performance will reduce until a dealer initiates a manual regeneration.

DPF problems

The most common issue with DPFs relates to inappropriate vehicle use or selection.  Vehicles that spend their lives in slow moving and stop / start traffic without regularly having the opportunity to achieve regeneration conditions will have on-going problems.  
  • The usual symptom is that the DPF malfunction warning light will illuminate, indicating that the DPF is becoming restricted.
  • The vehicle must then be driven the specified distance and speed to allow regeneration to occur.   
  • Failure to heed this warning will result in engine power being severely reduced and a trip to the service department for a manual regeneration. This can often include other work, such as an engine oil change.

Vehicle selection  

In view of the potential operational issues, drivers who spend most of their time in slow city traffic should consider if a DPF equipped vehicle is an appropriate choice for them.