Keeping Your DPF Filter Clean: Everything You Need to Know

The particulate filter also known as the DPF filter, is one of, fortunately, the few problem areas in today’s diesel car. As a result, there are many ways to deal with it. But to understand the main nuances, you need to know what DPF is.

Who is DPF for?

A DPF is a particulate filter in the vacuum pipe of a diesel car; it is needed to trap particulate matter which, together with nitrogen oxides and carbon dioxide, pollutes the atmosphere. This device is found on all diesel cars sold in Europe since 2009.

The particles that have retained the filter one way or another fill its ceramic honeycomb. But, fortunately, there is no need to immediately replace an expensive filter, which costs hundreds of euros – engineers have provided options to clean it. Although it should be said right away that everything is just a delay, and on a used car the DPF must be replaced or removed at some point.

Cleaning the particulate filter

The DPF filter can be cleaned in several ways, all of which are interconnected, as a sequential operation of different stages.

Stage 1 recovery (passive). In fact, this is the self-cleaning of the filter, provided by the factory designers. When the engine under load works for a long time, the filter heats up so that the juice collected in it burns out naturally. In addition, this is assisted by a metal catalyst that is inserted into the filter honeycomb. However, the engineers themselves admit that this method only gives temporary results.

Second level regeneration (active). Here we are talking about a special method, which, however, is also considered self-cleaning. The car automatically adjusts, based on data from several sensors, deciding that the filter begins to provide good resistance to exhaust gases. After this, the diesel fuel system supplies more portions of fuel to the intake specifically to increase the temperature of the exhaust gases. In addition, the extra part of fuel is supplied to the cylinder just before the opening of the exhaust valves, so that the diesel fuel burns out in the exhaust system, giving enter the filter.

But to successfully clean the filter, two conditions must be met. Therefore, a diesel engine must work under load and at sufficiently high speeds. In addition, cleaning requires a certain time, about 15 – 20 minutes. And this is where the problems begin. To fulfill the first condition, the electronic engine control unit activates the “burn” mode when the car moves on the road. But the second condition cannot always be met regarding the length of the process. And so, the filter, which is not cleaned again and again, is finally filled with soot so that it is not “bound” with resins, burned out even under favorable conditions. Accordingly, most of the cells are still clogged, automatic regeneration has to turn on more and more often – and the driver understands that he needs a lot of preparation to replace the DPF filter. …

Active cleaning (forced). A diesel car with a DPF filter always closed (a light on the dashboard warns about this) sometimes starts badly, accelerates worse and consumes more fuel than it should. In the end, it will be clear that normal self-cleaning is not enough and that urgent measures are needed – in particular, urgent cleaning of the filter. In fact, this is the same normal cleaning, but initiated by a person: the renewal algorithm is activated through a diagnostic scanner at the service station, according to the characteristics of a specific diesel model.

Just like when you “calcining” the filter goes away, during exhaust cleaning the program increases the speed of the engine and injects more fuel into the combustion chambers. At the same time, the electronics maintain the composition of the fuel-air mixture at the best level for burning soot. At the same time, the temperature in the exhaust manifold and the filter is monitored (through a standard set of machine sensors). A temperature of around 600 – 700 degrees is enough to clean honeycombs, but when more levels rise, the software reduces the portions of fuel sent to the nozzles. After overheating is eliminated and the exhaust system is “ventilated,” soot combustion is turned on again. This can be done repeatedly, and generally the process takes up to an hour until the sensors report a reduction in filter resistance.

Flowing. It happens that the owner missed the last moment when it was possible to clean the filter using one of the above methods, and the soot in his channels was completely baked. Then they try to wash the DPF honeycombs with a special solution. There are two options here: remove the filter and wash it separately, or leave it in place and insert a solvent drug through the sensor holes. More often, the technology involves soaking the filter in a liquid for several hours, and then washing out the soft deposits with a stream of the same solution or normal water.

Additives for diesel fuel

Owners of heavy diesels have another opportunity to prevent the particulate filter, or rather, postpone the washing in time, or even pass this procedure as a “relay race” to the next owner of car. We are talking about a diesel fuel additive that helps clean the particulate filter while the engine is running. A dosed portion of the substance is added directly to the tank and, according to the manufacturer’s instructions, its effectiveness lasts for several thousand kilometers. Experts believe that these drugs are very effective, but keep in mind that, in the first place, they do not help to burn out existing juices, but prevent the accumulation of “reserves” new.

In short

When you decide to clean the particulate filter, keep in mind that unprofessional actions can lead to problems with the car as a whole. For example, an inexperienced technician, when “frying” it, can overheat the engine’s turbine so much that it requires major repairs. The filter also does not accept temperatures above 1000 degrees, and you also need to be able to monitor this. And to keep the cleaning under control, you need to have a computer scanner as well as knowledge and theoretical knowledge. That is, for this important procedure, look for a proven service and do not trust your diesel engine to random experts.