Don’t let your DPF get too cool this Christmas.

Posted on December 23rd, 2020 by Rob Marshall

Don't let your DPF get too cool this Christmas.

While diesel cars have attracted much negative press recently, many owners strive to keep existing cars in good condition. However, in bids to make diesels less polluting, modern versions possess diesel particulate filters (DPFs). Pictured with this blog is a cutaway example.


The DPF is a canister, fitted to the exhaust system, which traps soot particles. The soot burns off, by being super-heated during a process called ‘regeneration’. If the DPF cannot get hot enough, the soot accumulation can block the exhaust. Apart from damaging the DPF, the situation can cause turbocharger and engine problems.


Fortunately, DPFs are very reliable but they become blocked for two reasons. Either an engine fault results in excessive soot production, or the car is subjected to too many short, or low-speed journeys, so that the system cannot get hot enough to burn away the soot and empty the DPF.


While we received member reports of DPF blockages, experienced during lockdown earlier this year, the problem is becoming worse now that the weather is colder and many motorists are not undertaking lengthy journeys during the festive period.


If your car is diesel-powered and you are driving short trips only, but a dashboard warning has not notified you of a potential blockage, consider that fuel additives can help the DPF achieve higher temperatures than normal to aid the regeneration process. Note that these preventative measures should be advertised as DPF regeneration aids and differ to DPF cleaners, which help to resolve a partially-blocked DPF situation.


Apart from selecting the correct additive, follow the information carefully, before dosing the fuel tank. Should the instructions state that the product should be added to a full tank of diesel, do not add it to a quarter tank, for example. Garages are discovering DPFs that have cracked/melted internally because of overheating, due to the driver over-dosing in a mistaken belief that more additive will deliver superior results. It is an expensive error, because the only remedy is a replacement particulate filter assembly.