Diesel Particulate Filters or DPF filters have been fitted to modern diesel vehicles for around the last ten years. This is an effort to reduce harmful exhaust emmisions and meet stricter emission levels. The DPF filter uses a combination of clever internal design and precious metals to collect and retain soot particles within its filter.

There is much debate as to how effective DPF filters actually are in terms of reducing carbon and other harmful emmisions from the exhaust. This is because these soot particulates will eventually leave the system one way or another, either dumped out through the DPF‘s own regeneration process, or when it is eventually destroyed.

While they do perfom well, problems can commonly occur which will cause them to block prematurely. When this happens a warning light will appear on the dash, and the vehicle may reduce power and enter what is called a ‘limp home’ or ‘safe mode’.

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DPF Regeneration

There are many reasons why a DPF can block. During normal driving, the unit will periodically regenerate or burn off the soot it has collected. It does this by communicating with the Engine Control Unit (ECU) which monitors the pressure using a sensor. When the output of the sensor reaches a pre-determined level the EGR valve is shut, the glow plugs are activated, and the ECU injects more fuel, raising the combustion temperature to burn off the soot and reduce the back pressure.

For DPF Regeneration to function correctly, certain conditions must be met. The vehicle must be driven at a constant speed (60mph or above) in high gear for at least 20 minutes. There must be no faults in the ECU, and all emissions components must be functioning correctly.

These are just a few of the most common causes of DPF blockage:

  • Lack of vehicle use on the motorway.
  • Frequent short journeys.
  • Engine management faults prevent regeneration from taking place.
  • Faulty glow plugs.
  • EGR and Turbo faults.
  • Pressure sensor failures.

Our engineers will carry out a full diagnostic assessment of your vehicle. We begin our process by checking for fault codes and monitoring live data. If no faults are present and we find the DPF is not excessively blocked, we have dealer level software to force regeneration. When faults are found, we will rectify these faults first before attempting regeneration.

Diagnostics and DPF Regeneration costs vary depending on the cause of the blockage, the extent of the damage, and time taken to diagnose and rectify the faults. We have an honest pricing policy, and our customers are kept informed at every stage of the process.