Are you having problems with your DPF?

A diesel particulate filter (DPF) is a filter that is specifically designed to collect the soot created when diesel is burned. As a result, it prevents harmful particles from being released into the atmosphere.

In fact, this process plays a critical role in reducing environmental pollution caused by diesel engines. Diesel particulates result from the incomplete combustion of diesel fuel, which produces soot particles. Additionally, soot and other emissions from diesel engines contribute significantly to particulate matter pollution in the air and are hazardous to health. While particulate filters are highly effective in dramatically lowering the number of particulates emitted from diesel vehicles, they still require routine maintenance. For this reason, most filters need to burn off the trapped particulates regularly—a process known as regeneration. Otherwise, if regeneration does not occur when needed, it can result in clogging and cause performance issues.

DPFs are used to help tackle the increase of global carbon emissions that come from more vehicles being on the road. The filter collects the soot to act as a barrier to these emissions and stops them from being released into the environment. This is why most modern cars come with a DPF included, especially since these filters are mandatory in all diesel motors. The soot needs to be cleaned off – but as we will discover why below, this does not always happen.

A DPF can hold a certain amount of soot, but not a huge quantity, so it needs to regularly go through a process of regeneration in order to clear out the soot and allow the vehicle to operate correctly. Regeneration occurs when the filter reaches a sufficiently high temperature, allowing the soot to be converted to a much smaller amount of ash.

To allow the DPF to automatically regenerate, the engine should be used regularly at a sufficient speed, to ensure a high enough temperature of the exhaust gas is reached. Although it may vary from manufacturer to manufacturer, typically a vehicle must be driven at 50mph or above for at least 20 minutes in order to automatically regenerate the filter. During the regeneration phase, high temperatures in the filter may cause a slight smell, especially during the first regeneration.

Stop/start short journeys at low speeds are the main cause of blocked diesel particulate filters.  If a car spends most of its time being driven around town on short start-stop journeys, the exhaust doesn’t get up to temperature so the soot doesn’t get burnt off and the DPF does not ‘regenerate’ on its own. 

Other most common reasons for DPF failures include a clogged EGR Valve causing excess soot, faulty fuel injectors sending too much fuel to the air/fuel mixture, wrong type of engine oil, high mileage car will find regeneration harder, low fuel level – generally less than a quarter of a tank – will prevent regeneration taking place.

DPFs are designed to last in excess of 100,000 miles but if the drivers fail to operate the vehicle correctly, it will fail a lot earlier

When a warning light stays on, turns red, or is joined by other DPF indicators, it’s essential to act fast. Otherwise, the issue can escalate quickly.

Often, ignoring these warnings leads to more damage. As a result, what could have been a simple fix turns into a costly repair.

While some garages offer forced regeneration to clear blocked DPFs, this is typically just a temporary solution. In fact, it may only delay the problem for 2–4 weeks, after which it often returns.

The real issue, however, usually remains unsolved. Because of this, the filter becomes more clogged over time. Consequently, your vehicle may emit more smoke, lose power, or enter ‘limp mode’.

Worse still, certain models won’t restart after reaching a mileage limit. Therefore, driving with a blocked DPF not only reduces performance but also risks damaging other components — eventually leading to far more serious and expensive problems.

When you see a flashing DPF warning light, you may consider removing it to solving the problem. This is not a great move for the planet and is, as mentioned, illegal in some places. Moreover, as of recently, cars that have had their DPFs removed will fail their MOT. It can be done, and you will find companies offering this service online, but it is just not worth it. It can even invalidate your motor insurance.

Diesel particulate filters are very expensive. A new one from a car manufacturer can cost £1,000 and £3,500, plus any diagnostic or labour charges, There are now other suppliers of diesel particulate filters that charge less, but be careful as they must still have the correct Type Approval or they may not work correctly and end up costing you more in repairs leaving you again with high repair bills.

It is natural that your DPF will become clogged, especially if you do not make frequent long-distance journeys. However, there are ways of helping your DPF stay clean. You need to make sure you use the right type of oil. Choose oil which is low SAPS. The fewer number of sulphate ash particles the less chance of your DPF clogging up. The second way to keep your DPF clean is to get a professional DPF cleaning company to take a look at your DPF at regular intervals.

If you suspect that your DPF is clogged or notice the warning light appearing, then it’s essential to take immediate action. Instead of waiting for the issue to escalate, we provide a highly effective and affordable solution. As a result, using our state-of-the-art equipment, we offer on-the-spot roadside DPF cleaning, which helps you get back on the road quickly and efficiently.

Moreover, whether you drive a van, car, or lorry, our advanced tools are capable of assessing your DPF’s performance and significantly reducing soot and particulate levels. In addition, we deliver a comprehensive before-and-after performance report, giving you confidence in a job well done. Ultimately, our service helps you avoid costly replacements and ensures your vehicle continues to run smoothly.