Diesel particulate filters have become a standard feature on most diesel cars and vans since 2009. Their primary function is to stop soot in the exhaust from passing into the atmosphere. Vehicles that have a DPF fitted have lower emissions by up to 80%, but the trouble is this technology comes with its own set of problems, and a blocked DPF is something serious.
In order to maintain its performance, a DPF needs to be emptied on a regular basis. You can do this passively via a process called regeneration, which happens when you drive on motorways or fast national roads where the temperature of the exhaust is high enough to burn off the built-up soot. During this process, only a tiny ash residue is left, which cannot be removed, but in a car used correctly, a DPF can go for over 100,000 miles.
Cleaning a DPF via Active Regeneration
There are times when passive regeneration is not possible, especially when it comes to drivers who do not use their vehicle on motorways but only for urban driving that requires lots of stops. Active regeneration is another way of cleaning your vehicle’s DPF and this takes only 5 to 10 minutes to complete. During active regeneration, the engine control software senses that the DPF is about to become blocked and injects some extra fuel into the engine to raise the temperature of the exhaust and trigger the regeneration process.
This process is generally initiated after approximately every 300 miles, and you may notice a couple of signs during active regeneration. These include a faster engine idle speed, increased fuel consumption, a different sound of the engine, the cooling fans running, and a hot smell from the exhaust.
Cleaning DPF vs. Removing It
Replacing your DPF can bring about an eye-watering repair bill, so it is always a good option to attempt cleaning first. If the filter becomes partially or completely blocked, you may need the help of a professional service like us to clean it. In some circumstances, the engine refuses to regenerate in the normal way, and this could be due to a failed component. As such, before paying hundreds or thousands to replace your DPF, you should first investigate whether there are other underlying reasons elsewhere responsible for the blockage.
Keep in mind that it is against the law to remove and not replace a DPF of your vehicle, so your only option when you deal with a completely blocked DPF is to have it cleaned or replaced. The bad news is that in the case of many vehicles, the replacement may be costlier than the actual value of the car. Before replacing your DPF it would be wise to get a quote from us to have it professionally cleaned.
If for whatever reason this fails, replacing the DPF is the only thing left to do. You need to be aware of the fact that your vehicle will fail its NCT if you do not have a DPF where originally fitted So Clean, Replace or Fail. Never remove without replacing.
Can I Clean My Own DPF?
You can clean your own DPF using a DPF cleaning additive, which is a chemical solution that you add to the fuel tank to aid the passive or active cleaning of a DPF filter. However, these additives, even though they are an inexpensive treatment for a blocked DPF, are not a guaranteed way to get rid of all the built-up soot. They also do not work well if the DPF is mostly clogged with ash. The additives that we sell are recommended after cleaning or to maintain a replaced DPF.
How to Clean a Blocked DPF
To clean a blocked DPF, start by checking the instructions in the owner’s manual regarding this issue. In the majority of cases, you only need to follow a couple of simple steps that work on most vehicles. First, make sure that there is a least 1/4 of a tank of fuel and that the engine management light is not on. Next, turn on as many of the electrical items as possible such as heated seats, air conditioning, heated rear window, lights and so on. By doing so, the engine will work harder and will reach the required hot temperature quicker.
Next, find a motorway or a dual carriageway where can maintain a constant speed or about 50 kilometres without having to stop. Choose a gear that can maintain 2000 rpm at a constant speed within the speed limit, and drive for about 50 kilometres. By doing so, your DPF filters should automatically regenerate without costing you any money. However, if the DPF light remains on after attempting this type of memory generation, your filter will require professional cleaning by us. Give us a call to get your car booked in at a convenient time that suits you.
How to Avoid Future DPF Problems?
To avoid future DPF problems, you need to make sure that normal regeneration of the engine is not prevented in any way. Things that prevent normal regeneration include using the wrong type of engine oil and frequent short journeys where the engine does not get the chance to reach the correct temperature to start passive regeneration. You should always make sure you consult the vehicle’s handbook when it comes to selecting the correct type of engine oil.
Excess soot may be caused by a problem with the fuel system, whereas a warning light on the dashboard of your vehicle indicates that you are dealing with a blocked DPF. A low fuel level, usually less than 1/4 of the tank will also prevent the process of active regeneration. You should also avoid going over the recommended service interval for your vehicle to avoid further DPF problems.
All DPF filters need to be kept clear of built-up soot in order to run properly. To achieve this, the on-board computer system of the vehicle monitors the state of the filter constantly by measuring the exhaust pressure that enters and leaves the DPF. The computer is then able to calculate the state of the filter as well as the point at which it needs active or passive regeneration. Taking care of this problem before the DPF becomes partially or completely blocked is the safest way to avoid paying high repair bills for professional cleaning or replacing the DPF entirely.