What is a DPF

You have probably got to this page due to either a concern about buying a Diesel with a DPF or you have already purchased your car and are now having DPF issues. But just “what is a DPF?”

A DPF or Diesel Particulate Filter is a blocked off honeycomb filter, it is referred to as “blocked off” as you can’t see all the way though it. It has been designed to stop the amount of soot / smoke that is released from a Diesel exhaust, once you are aware of their existence it is plain to see that a lot less smoke comes out the back of a new Diesel compared to a Petrol engine.

They are usually located as close as possible the engine where the exhaust gasses are at their hottest. To the right you can see an example of where the DPF is situated.

As you can probably see, whilst their are benefits of having the DPF filter fitted, the reason for manufacturers install them is to ensure they keep up with EU regulations, with countries such as Germany having laws in place where Diesels can only come into city centers if they have a DPF fitted.

However there are a number of downsides to the DPF

  • Reduced Economy
  • Wasted Diesel during DPF regeneration
  • More backpressure
  • Less power
A lot of owners are having DPF removal or DPF delete performed which is the process of removing the filter and modifying the ECU to run with the new setup. This results in more power and better economy and whilst is an expensive procedure it is cheaper than a DPF replacement which can easily cost £2k. Additionally after 100,000 miles the DPF filter can become blocked with ash that will not burn off during a regeneration at this point the only option is removal or replacement of the filter.