The target is for 80% reduction in diesel particulate emissions, but this technology also comes with some problems, with more and more calls to automobile associations with related filter warning lights on, indicating a filter blockage.

These Diesel Particulate Filters need to be cleaned regularly, mostly through a process called regeneration, either ‘active’ or ‘passive’ regeneration, where the collected soot is burnt off at high temperature, effectively renewing or regenerating the filter.

The additive operates in two ways. First, it uses a catalyst to adhere to the soot particles during combustion, lowering the temperature at which they can be burnt off at. Secondly , the additive also increases the fuel burn temperature, in turn increasing the exhaust temperature , which increases the temperature inside the soot trap ,burning off the soot, regenerating the filte

What is a FAP?
The DPF is also referred to as a Diesel Particle Filter and a FAP (Filtre à Particules). The term FAP comes from the french diesel cars, mainly Peugeot & Citroen which have been fitted with this technology since 2000.

The DPF is like a big honeycomb ceramic filter inside, similar in ways to a catalytic converter – except the holes are much smaller and square not circular. As the exhaust gasses flow through it, the DPF captures the harmful molecular diesel particulate (soot), which is in size a thousandth of a millimetre. Once the DPF has reached captured soot levels of between 25-45% the on-board engine management system will activate a “Regeneration Cycle” which increases the exhaust temperatures to burn off the soot inside the filter so that it is removed safely.

When the DPF requires regenerating (self-cleaning) you need to refer the owners manual of your vehicle for specific driving instructions to successfully carry out a regeneration. In general, the DPF warning lamp would be illuminated and you are required to drive on a dual-carriageway / motorway for at least 20 miles at a constant speed of 40-50mph in 4th gear until the warning lamp goes out. The warning lamp will only go out once the DPF Regeneration has been completed successfully.

There are many setups manufacturers have chosen to get the best possible results from a regeneration cycle and to make it as successful as possible. Some of these setups include:

Additive Fluid Systems

5-Cylinder Engines

5th Injector in Exhaust

Pre-Cycle & Post-Cycle Injection

Some vehicles will use one of the above and some will use a combination to try and find the best solution to regenerating a blocked DPF.

Not in all cases is it possible to complete a successful DPF regeneration and there are many factors which can affect this process. Once a DPF is blocked beyond a successful regeneration

The term “What is a DPF” is searched for 49,500 times a month on Google and is a growing concern for motorists. We offer free impartial advice and hope to help motorists around the world resolve all their DPF related issues ,.If you’re vehicle has been affected and would like to know what is a DPF then you’ve come to the right place – please share this website to help others understand what is a DPF.

A diesel particulate filter, sometimes called a DPF, is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. Wall-flow diesel particulate filters usually remove 85% or more of the soot, and can at times attain soot removal efficiencies of close to 100%.

The composition of the soot particles varies widely dependent upon engine type, age, and the emissions specification that the engine was designed to meet. Two-stroke diesel engines produce more particulate per unit of power than do four-stroke diesel engines, as they burn the fuel-air mix less completely. Historically medium and heavy duty diesel engine emissions were not regulated until 1987. Since then progressively tighter standards have been introduced for both On-Road and Non-Road diesel engines.

The increasingly stringent emissions regulations that engine manufactures must meet mean that eventually all on-road diesel engines will be fitted with them. The California Air Resources Board (CARB) has established diesel emissions regulations which—with variance according to vehicle type, size and usage—require that in-use diesel engines (in California) be retrofitted, repowered or replaced in order to remove at least 85% of particulate matter (PM) emitted from diesel engines. Retrofitting the engines with CARB verified diesel particulate filters are one way to fulfill this requirement.

Filters require more maintenance than catalytic converters. Ash, a waste product of burning away the soot during regeneration, builds up on the surface of the filter and will eventually clog the pores.. Regular filter maintenance is a necessity.

Regeneration is the process of removing the accumulated soot from the filter. This is done either passively (from the engine’s exhaust heat in normal operation or by adding a catalyst to the filter) or actively introducing very high heat into the exhaust system. On-board active filter management can use a variety of strategies:

All on-board active systems use extra fuel, whether through burning to heat the DPF, or providing extra power to the DPF’s electrical system, although the use of a fuel borne catalyst reduces the energy required very significantly. Typically a computer monitors one or more sensors that measure back pressure and/or temperature, and based on pre-programmed set points the computer makes decisions on when to activate the regeneration cycle. The additional fuel can be supplied by a metering pump. Running the cycle too often while keeping the back pressure in the exhaust system low will result in high fuel consumption. Not running the regeneration cycle soon enough increases the risk of engine damage and/or uncontrolled regeneration (thermal runaway) and possible DPF failure.

DOCs is the other diesel retrofit system. They are devices that use a chemical process to break down pollutants in the exhaust stream into less harmful components. More specifically, DOCs utilize palladium and platinum catalysts to reduce the particulate matter (PM), hydrocarbon based soluble organic fraction (SOF), and carbon monoxide content of diesel exhaust by simple oxidation