DPF and Anti pollution faults

DPF and Anti pollution faults

Due to ever tightening European emission legislation, modern diesel vehicles are being fitted with pollutant filtering systems that physically collect harmful particles and soot from your engine exhaust gases. The Diesel Particulate Filter (DPF) will therefore become blocked with particles over time and with use.

Vehicles with DPF’s fitted will also be equipped with the ability to self clean the filter. This procedure is usually started automatically when the conditions are suitable, this will often be when the vehicle is travelling at a sustained speed of over 40mph and the engine and exhaust system are at operating temperature. The process commonly  takes around 10-15mins, so ideally motorway driving is the perfect time for your DPF to self-clean or ‘regenerate’.


The regeneration process involves raising the DPF temperature to 5-600 degrees centigrade, using controlled post injection of fuel. At this temperature the particles contained in the DPF are vaporised, cleaning the filter very effectively. Some vehicles (Peugeot/Citroen and Ford notably) have an additive tank, situated adjacent to the fuel tank, that injects a small quantity of a special fluid into the fuel tank with every refuel. The job of this fluid is to lower the vaporisation temperature of the soot particles held in the DPF therefore making regeneration more effective and easier to attain.

Faults with this system

The most common fault we find with these systems is of course blocked DPF’s , very common with vehicles that are used primarily for town and local driving, and rarely used on the motorway or at higher sustained speeds, other issues are damage to DPF temperature and pressure sensors due to the extreme environment they operate in, and running out of additive, this normally needs a top-up every  70-80,000 miles.

At Whitstable Motor Services we are equipped to re-fill additive tanks, diagnose and repair sensor and system faults, and to force regeneration of DPF’s . The latter can be done at our workshop or on the road by putting the vehicle into a high efficiency regeneration programme, that would not normally occur in everday use.

Please feel free to contact us if you have any issues with your DPF, or would like to discuss any other service for your vehicle.