Diesel Particulate Filter Services

We provide a range of services from regeneration to replacement for customers suffering difficulties with their Diesel Particulate Filter (DPF) Systems.

Following the MOT changes introduced in 2014 we NO LONGER RECOMMEND HAVING DPF SYSTEMS REMOVED FROM YOUR VEHICLE AS THIS CAN CAUSE FAILURE OF THE MOT.

FAILURE TO HAVE YOUR DPF SERVICED WHEN INDICATED CAN LEAD TO FAILURE AND AN EXPENSIVE SERVICE. PLEASE DO NOT LEAVE IT TOO LATE !

Diesel Particulate Filter (DPF); How they work and why they cause problems

The DPF looks similar to a traditional exhaust silencer but is mounted close to the engine. Inside is a complex honeycomb ceramic structure designed to filter the exhaust gases while minimising flow reduction (which would otherwise limit performance). By forcing the exhaust gases through the walls between the channels of the DPF, the particulate matter is deposited on the walls, so reducing the amount of air pollution. Once the DPF reaches a certain level of ‘Saturation’ it performs a regeneration cycle to burn off the particulate matter inside the filter.

• A car used significantly on motorway journeys will generally run at warmer temperatures and therefore produce less particulate matter than one used in a stop/start city environment. Further, motorway driving provides an oportunity for automatic regeneration more often and effectively as it is the perfect driving environment for the regeneration process to occur,
• Vehicles used for short trips and low speeds produce more particle matter and do not often reach the conditions required to initiate automatic regeneration of the DPF; requiring manual intervention to clear the DPF system of soot build up,
• Larger diesel vehicles with low duty cycles (short trip, low speeds) will suffer particularly with soot build up in the DPF.

Diesel Particulate Filter (DPF) Fault Diagnostics

When a fault is first indicated with the DPF filter it is important to first confirm the fault is with the DPF itself and not one of the sensors associated with the exhaust / DPF system. This is achieved by reading the fault codes from the vehicle, confirming these do not indicate a sensor failure and confirming the soot levels within the DPF are within the regeneration zone.

Diesel Particulate Filter (DPF) regeneration (cleaning)

The Diesel Particulate Filter (DPF) indicator signifies your vehicle's DPF filter has not been regenerated (cleaned) and will require a manual / static regeration. Once this service is indicated it is advisable to have the procedure carried out as soon as possible to avoid long term and possibly expensive damage to the filter - (a replacement filter can cost up to £1,800).

Why does the DPF need regeneration / cleaning ?

The DPF filter traps carbon particles, filtering exhaust gases as they pass through. Like any filter this must be regenerated (cleaned) to restore it to full operation. Under normal circumstances the regeneration process is carried out by the car itself when the engine/emissions management system detects the DPF is in need of regeneration. However Diesel vehicles used only for short journeys do not provide the system sufficient opportunity to regenerate the DPF, resulting in a fault developing. This fault is indicated by the DPF / engine management fault indicator illuminating and/or a fault message on vehicles equipped with display centers.

What is DPF regeneration / cleaning ?

When a fault develops with the DPF filter, indicating manual regeneration is required, this is completed in combination of the workshop and driving the vehicle. Using our service computer we first tell the car to initiate the DPF regeneration process and then run the car at load. During the regeneration process sufficient heat must be generated for long enough for the regeneration to complete.

Note - Once a DPF fault is indicated, automatic regeneration will almost never be completed and continued operation will damage the DPF filter.

What if I don't have the DPF Regenerated ?

Once the Engine Management Fault / DPF Fault Indicator has illuminated this indicates the DPF has not been regenerated through the normal driving range of the vehicle and requires manual/static regeneration.

Failure to have the regeneration completed at this stage could render the filter itself beyond repair and require complete replacement. A DPF that reaches 90% or approx. 45 grams full will be beyond regeneration and require complete replacement.

Depending on your vehicle make and model a failed Diesel Particulate Filter can cost upwards of £1000 to replace.

How long does the regeneration take?

The DPF regeneration cycle takes approximately an hour and a half (1 1/2 hours) to complete and can be completed as part of a routine service.

Why you cannot manually regenerate the Diesel Particulate Filter yourself

If you use your diesel vehicle for mainly short trips and the engine management light illuminates it maybe possible to have the car enter regeneration itself by simply using the vehicle over a long distance. However this is not recommended and is seldom successful because;

• You cannot guarantee the vehicle will enter regeneration mode (we use our diagnostic equipment to tell the car to enter regeneration mode)
• You must create significent engine load / heat to enable AND complete the regeneration cycle
• The fault indicator will not switch off typically without the fault code being cleared (you may never know the DPF has been regenerated!)

DPF Additive Replacement

Some vehicles (Volvo, Citroen and Ford particularly) in addition to the standard DPF system incorporate an additive release system. This system releases controlled amounts of an additive into the fuel system to reduce emissions and promote cleaning of the system. This additive is held in a resevoir in the vehicle and when exhausted will need refilling.

Refilling of the additive system is also indicated by the DPF fault indicator and an additional text advice where these systems are installed. This fault usually coincides with the requirement to regenerate the DPF. Failure to have the additive refilled will affect the vehicles performance and lifespan of the DPF system and should be addressed.

Diesel Particulate Filter (DPF) Replacement

When a DPF system becomes too full of soot it will be unable to regenerate succesfully and require replacing. In normal use with normal automatic regeneration this will still occur. However if a DPF becomes unable to regenerate either automatically or manually it will require a full replacement.

Replacement of the DPF system requires the removal of the DPF assembly from the exhaust system and replacement with a new or approved unit. We do not recommend the installation of reclaimed DPF systems unless these have been certified as soot free before installation.

A typical DPF replacement can start at £900 and depending on vehicle maybe in the order of £1800.

Diesel Particulate Filter (DPF) Removal and your MOT

Vehicles fitted with a Diesel Particulate Filter (DPF) at manufacture that are identified during an MOT inspection to have had the DPF removed or disabled will now fail the vehicle MOT.

While the DPF itself and its correct operation is not part of the test (provided the vehicle emissions are within range) and a vehicle with a faulty DPF may still pass an MOT inspection, VOSA have advised all testing stations that identified removal or disabled DPF's should be classed as a vehicle failure.

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