What is the diesel particulate filter? - Concesur Group

If you have driven a diesel car in the last decade, you will be aware of the existence of the diesel particulate filter, a component attached to the engine that has anti-pollution functions. This element is mandatory on both diesel and gasoline cars to comply with the WLTP emissions protocol standards that came into force in 2021. But what exactly is the particulate filter(DPF) and how does it work?

Present in both new Mercedes models, such as the Mercedes C 220 d, and older models, the diesel particulate filter, also known as DPF, reduces the levels of pollutant emissions produced during diesel combustion inside the engine. This enables the cars to comply with the Euro 5 and later emission standards.

What is the FAP of a car?

The particulate filter is a device located in the car's exhaust system. It is responsible for retaining in its porous walls the polluting particles generated by the engine, thus reducing emission levels. The system accumulates what is known as particulate matter inside the filter and later incinerates it.

The entry into force of the Euro 5 standard in 2009 brought with it a significant restriction of exhaust emissions. Focused on reducing pollution from the then-popular diesel cars, this regulation involved the installation of anti-particulate filters in all new vehicles. From 2015, the arrival of the Euro 6 standard did the same for gasoline engines, which have also received their own anti-particulate filter, known as GPF for its acronym in English.

How does the FAP work?

The operation of the diesel and gasoline particulate filter is based on the capture of particles and their subsequent incineration. The device filters the soot generated during combustion through small porous cells housed inside. Sensors constantly analyze the volume of soot in the filter and warn the car's control unit that the filter's saturation limit is being reached.

This soot saturation limit is set at approximately 40%. At this point, the engine raises the temperature to 700 degrees to force the regeneration of the particulate filter, a process called pyrolysis. The soot is burned, being emitted to the outside in a more purified and less polluting form. Regenerations are carried out automatically approximately every 1,000 kilometers, in a process that lasts between 2 and 3 minutes.

Which cars have a particulate filter?

Since 2009, the particulate filter has been mandatory on all diesel cars. However, there are some models that were already equipped with it before, even in 2006. In the case of gasoline-engine vehicles, the filter has been part of their mechanics since 2015, although its implementation has been staggered, becoming fully mandatory with the arrival of the WLTP emissions protocol in 2021.

Thus, the FAP is present in most new cars sold today. This also includes hybrid and plug-in hybrid vehicles, since their propulsion system is based on a gasoline or diesel engine.

How to clean the diesel particulate filter

As a general rule, the diesel particulate filter is cleaned by automatic regenerations. However, you can perform a manual regeneration to force the system to desaturate the filter. To do this, it will be necessary to go out on the road and drive for a few minutes at a high engine speed.

It is recommended that you drive between 2,500 and 3,000 revolutions per minute for 20 to 30 minutes. In order not to exceed the speed limits, you can drive in a lower gear (fourth gear in a manual car, for example). In this way, the internal temperature of the engine will rise and this will favor the regeneration of the anti-particulate filter.

If this method does not work, you can go to the Mercedes Benz Official Service of Concesur Group, where our specialized technicians will perform a forced regeneration of the particulate filter. Keep in mind that if the system reaches a high level of saturation, the only solution may be to replace the particulate filter.

Price of changing the particulate filter

How much does it cost to change the particulate filter? This is not a cheap repair, as the device itself is already an expensive replacement. Depending on the vehicle, the filter and the brand, the price of changing the particulate filter can range from 800 € to 3,000 €.

There are some signs that something is wrong with the particulate filter that can help us identify whether a particulate filter replacement is necessary or whether a forced regeneration is sufficient. In some models, a particulate filter warning light will come on, which is usually yellow and will indicate that there is a fault in the system. The engine malfunction warning light may also appear. In this case, you may experience some loss of power if the filter is saturated, as the car will protect itself by reducing the workload to prevent further build-up of carbon inside the filter.

Diesel particulate filter problems and how to avoid them

To avoid having to face the high costs of replacing the particulate filter, there are a series of tips that will allow you to keep it in good condition and thus prolong its useful life. Diesel particulate filter problems are generally caused by the type of driving you do.

Abusive city driving or driving at low engine speeds encourages the generation of carbon and its accumulation in the filter. In addition, driving at low revs or driving too short distances also limits the options for regeneration. For this reason, try to go out occasionally on the highway or freeway and drive a few kilometers at more than 2,500 rpm to help clean it.

It is also important to check the engine oil level periodically, at least once a month. At the same time, you should follow the maintenance programs established by Mercedes Benz. In this way, our technicians will be able to detect any anomaly in the system and make preventive repairs to avoid a major breakdown.

In Grupo Concesur we offer a complete after-sales service specialized in all Mercedes Benz models. Our technicians will advise you on the correct use and maintenance of your car's particulate filter. They will also advise you on possible revisions so that you can prolong its useful life. Make an appointment at your nearest Concesur Group Official Workshop and start taking care of the mechanics of your Mercedes Benz.