What you need to know about diesel particulate filters

Diesel Particulate Filters are an industry response to the ongoing tightening of exhaust emission standards for diesel vehicles. But vehicles fitted with them may not be an appropriate choice for everyone. 

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.

Things to note

The information in this article has been prepared for general information purposes only and is not intended as legal advice or specific advice to any particular person. Any advice contained in the document is general advice, not intended as legal advice or professional advice and does not take into account any person’s particular circumstances. Before acting on anything based on this advice you should consider its appropriateness to you, having regard to your objectives and needs.