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DPF Errors, Warnings and Problems

We have recently noticed a huge increase in the number of calls and emails we are getting from people with the DPF warning or error light flashing or showing on their car.

There are a number of points that seems to confuse a lot of people about DPF faults and Error Warnings.

Although each make and model has slightly different systems there are a few things in common with all DPF equipped cars and vans.

  • If the DPF light comes on without any other warnings, this is a normal event and just means that you need to follow the instructions in the owners handbook. This normally means driving in an appropriate gear, maybe sport mode on an automatic gearbox model, so that the engine speed is between 1,700 and 2,200 RPM for about 15 minutes or until the light goes off. This needs to be done continuously without stopping so a long stretch of dual carriageway or quiet motorway is probably ideal.
    • Its not the speed that you drive that allows the DPF to regenerate but the constant and higher than normal engine speed speed that allows the system to clean itself
  • If the DPF light comes on and is with a glowplug or engine management light then there is a problem with your car that needs to be diagnosed and fixed as an urgent matter. 

Many of the cars that have been brought to us recently for a "dpf problem" or dpf cleaning have not actually had a real problem with the DPF at all.

We are yet to see a DPF that needs replacing, these robust components have been designed to operate under extreme conditions and should not need replacing as they have been developed to catch soot and clean themselves as part of the normal driving cycle, they do occasionally require some assistance if the driving style and habits of the driver have not suited the process, but that should be all that is required if the vehicle is maintained according to the schedule and following the instructions in the owners handbook.

The problem is that if there are any faults that are recorded in the Engine Controller (often incorrectly called the ECU or Engine Management system) or any fault elsewhere that causes the car to go into "limp" or "get you home" mode, then the DPF will be unable to clean or regenerate itself.

A very good example was a vehicle that came to us recently to have the DPF cleaned as the main dealers had been unable to get the vehicle to regenerate itself and so they told the owner that a new DPF was needed at a cost of £1,600 plus fitting to resolve the problem. Fortunately the owner decided to bring the car to us for a second opinion. The problem was actually a fault with the braking and dynamical stability system that was causing the car to be in limp mode: once this problem was resolved the car regenerated the DPF successfully and all errors were gone.

If you have a DPF fault on our car, find a specialist that can correctly diagnose the real cause of the problem, failure to do so may end up costing more to have parts replaced that did not need changing and were really a waste of your time and money.

You should also be wary of the increasing number of "dpf cleaning companies" that are appearing from nowhere, many of the cars that are brought to us from all over the country to have the dpf cleaned do not actually need the dpf to be cleaned, they just need the problem that is stopping the dpf from cleaning itself resolving.

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