Diesel Particle Filters


  1. Problems due to driving style

  2. Rectification of vehicles forced into limp mode

  3. Removal of D.P.F and reprogramming to remove activation software.


We offer a D.P.F regeneration service for vehicles which have not been able to regenerate themselves due to driving styles. The Diesel Particulate filter is fitted to later diesel vehicles to remove harmful soot particles from the exhaust and store it until the management system regenerates the system when the vehicle is travelling at high speed on the motorway. The management system will start the process when the filter becomes partially blocked by injecting extra fuel into the exhaust and increasing the temperature to a lot higher degree than normal to burn off the soot and thus reduce the restriction within the filter. If a customer’s driving style is such that their vehicle is very seldom used on a motorway or regularly travel at low speeds and only do short trips, then there is a distinct possibility that automatic regeneration will not be performed and therefore the filter will become that blocked that the management system will force the fuel system into a limp mode and will have only limited performance.  

It has been found that the system cannot be cleared, even by dealer level diagnostic equipment, until regeneration has been performed. This can be done statically, in some cases, however if this is not successful,  a dynamic regeneration is required and can carried out on the road with the laptop connected to the engine management system via the 16 pin socket to access the dynamic test software. The process can take up to two hours to perform, depending on the severity of the blockage, and will be terminated by the computer when the restriction has been reduced to an acceptable level. The vehicle can then be driven normally back to base.

In some cases the blockage is so bad that the only way to cure the problem is to replace the D.P.F or remove it and have it cleaned by a specialist company. Due to the high cost of these units the latter is usually the cheaper of the two options. The most important lesson to be learned from this problem and the reason for the blockage is that, once rectified the same problem will occur, if the customer’s driving style is not changed.

If it is found that a change of driving style is not possible, then the only other option is to replace the vehicle with a later petrol engine that achieves a similar mpg and performance to the modern diesel vehicle. The removal option is no longer possible as the latest mot rules state that if a vehicle was originally fitted with a D.P.F. it must not be removed and must be in full working order. This means that all those customers that had their D.P.F systems removed will now have to have them refitted.