How to clean a diesel particulate filter

clean a diesel particulate filter

How can you clean a diesel particulate filter in your car? Our guide outlines the simple way to do it — and why you may not have to.

For some years now, almost all cars and trucks with diesel engines have been using so-called diesel particle filters (DPF for short). In the meantime, the filters from well-known manufacturers such as BMW, Ford, Mercedes-Benz, Opel and the TDI engines of the VW group (including: Audi, Seat, Skoda and Volkswagen) are mostly part of the standard equipment. However, it all started with two French manufacturers.

The Citroën C5 and the Peugeot models 406 and 607 were the first cars to be fitted with a diesel particulate filter as standard after the turn of the millennium. The particle filters are responsible for separating toxic substances from the exhaust gases. As part of the exhaust system, the proper functioning of the particulate filter is very important. The filter is emptied regularly through regeneration to prevent clogging. If the soot particle filter is clogged, this can damage the filter itself and the engine.

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How the DPF works and how to clean a diesel particulate filter

Here you can find out which different systems are available for cleaning the particle filter and why cleaning the filter is so important. The particle filters are responsible for separating toxic substances from the exhaust gases. Since the capacity of the filter is not unlimited, there are measures for regeneration. One differentiates essentially between active and passive systems.

The diesel particulate filter is also often referred to as a soot filter, which already gives an indication of how it works. The exhaust gases that flow through the individual filters are contaminated with fine dust particles. These particles attach to these filters so that they do not get into the air. Every diesel particulate filter is equipped with a sensor that measures whether the filter can absorb even more fine dust.

When the filter can no longer absorb fine dust, the process of DPF regeneration begins. The filter heats up to a very high temperature of around 600 degrees Celsius, which burns the fine dust particles.

Active regeneration

In active cleaning systems, sensors determine the current state of the soot particle filter. When a specified level is reached, the filter is automatically cleaned. Cleaning is carried out via the motor control. The timing of the fuel injection is adjusted so that the exhaust gas temperatures rise. The higher temperatures burn the soot that has accumulated in the filter and the filter is cleaned.

HOWEVER …. If the car is only used for short distances at low speeds, there is a risk that the particle filter will clog up completely. This can lead to increased fuel consumption. A lack of regeneration can not only damage the particulate filter, the increased exhaust gas back pressure can also damage the engine. In these cases, it may help to clean the filter by resorting to the method described under passive regeneration.

Passive regeneration

Passive regeneration vehicles require a certain temperature range to enable cleaning. Since this area is relatively high, motorway journeys at higher speeds are particularly suitable.

Our tip: If the message appears in the instrument cluster or in the on-board computer of your car that the particle filter needs to be cleaned, you should cover a suitable distance at a higher speed in a timely manner. The regeneration process should be complete after about 15 to 20 minutes.

How long does a diesel particulate filter last?

The driving style and the routes, which are largely covered, have the greatest influence on the durability of the diesel particulate filter. If the car is used very often for short distances, the lifespan is usually quite limited because the filter can clog more quickly. This happens because the engine cannot reach its operating temperature over short distances, which means that the fuel is never completely burned and more soot accumulates in the engine than normal.

In addition, diesel particulate filters have a natural limit in most cases, depending on the vehicle and manufacturer. For the multitude, the filters are around 120,000 and 240,000 kilometers. However, there are already some filters that can last a lifetime.

DPF retrofitting

Retrofitting a soot particle filter can be worthwhile. On the one hand, in some jurisdictions there is a government subsidy for the installation, on the other hand, it is possible that your car will receive the coveted green environmental sticker through the retrofitting. 

In the case of older diesel vehicles in particular, retrofitting a diesel particle filter can achieve a more favorable rating for vehicle tax and thus save money.