Diesel Particle Filters



Do you drive a diesel vehicle?  

If the answer is yes, then it is highly likely that you have a Diesel Particulate Filter (DPF). Did you know that failing to maintain it can lead to severe consequences for your car?

I am going to try and guide you through what it does and why, along with how to maintain it to ensure you get the most out of your vehicle.


What is it? 

A DPF is a filter that captures the soot emitted from your engine. This soot is incredibly hazardous for your respiratory system, so the filter helps stop it get into the air that you breathe.  As the filter fills up, your car will perform a regeneration to safely burn off the soot build up.  Following legislation in 2009, DPF’s became mandatory.


What makes my DPF fill up? 

Typically speaking, it is short journeys and low revs that enable the DPF to fill up. If you are constantly making short journeys which do not enable the engine to kick out extremely hot fumes, then the buildup occurs. This is normal, and not a problem, you just need to listen to your car when it tells you it is initiating a regeneration.


My car is telling me to do a regeneration, now what?

So, the important thing here is to not stop the car and keep driving, try to keep the revs at about 2500, this can be 30mph in 2nd gear. Another way to help the regeneration occur is to go on the motorway.


Types of regeneration

Spontaneous (Passive) – This usually happens when driving long distances at a higher speed, the engine is hot, so the fumes can burn the soot away. This is barely noticeable, although you may notice a bit of a shaky car and reduced performance for a short while.

Dynamic (Active) – This is the one where your car will prompt you to keep driving and not switch the engine off, just keep driving and after about 20 minutes the regeneration should be complete.

Service (Forced) – When the above two regenerations have not managed to be completed, your car will go into limp mode and you’ll be forced to go to a service centre or get the AA out.


My input

Around 39% of all cars in the UK are diesel so there’s a fairly high chance you will come across this problem if you haven’t already. If you are a driving instructor with a diesel engine, you’re even more likely. This is due to your typically low speeds and short journeys. It really shouldn’t be a big deal, so long as you understand the problem when it arises. Most DPF issues come from ignoring the regeneration process and letting your engine fail due to a blocked DPF. On the rare occasion it does become a problem, don’t even think of doing what an estimated 10,000 motorists are doing, and removing the DPF altogether. As of May, 2018 there will be more than a visual inspection and cars will instantly fail should they not have the pollution filter.


Danny Atkin

Transport Director

Surepass Ltd


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