Car Warning Lights Explained - What does the DPF Warning light mean?

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One of the many advantages of modern vehicles is their electronic system that constantly monitor vehicle performance. These onboard computer could flag up any potential issues before they become a bigger problem, saving you money before a costly repair or breakdown. When something isn't functioning correctly, your car computer would alert you by showing a warning light on the dashboard, sometimes accompanied by a message on the information display.

What is a Diesel Particulate Filter (DPF)?

If you are driving a diesel vehicle, one common warning light you may encounter could be related to the Diesel Particulate Filter, also known as DPF. DPFs have been fitted in diesel vehicles for over 20 years, particularly in larger vehicles such as vans and SUVs.

A DPF is a critical component designed to reduce harmful emissions by capturing soot particles from your exhaust. This not only helps improve air quality but also ensures your vehicle complies with emissions regulations.

How to recognise a DPF warning light?

The DPF warning light could look slightly different in vehicles depending on the make and model you drive. Typically, it resembles an exhaust pipe with dots or circles inside a box. If you are unsure what to look for, our experts at Eden are always available to assist.

What to do when the DPF warning light comes on?

If the DPF warning light comes on, it’s crucial to address it promptly. Ignoring the issue can lead to more severe and expensive damage. However, you may be able to resolve it yourself with a little knowledge about how DPFs work.

What DPF does and how it works?

DPFs are designed to self-clean through a process called "regeneration." This involves injecting fuel into the filter to increase its temperature, burning off the accumulated soot. For this to happen, the vehicle typically needs to maintain a speed above 40mph for a sustained period. This is why you might notice cars on the motorway emitting a brief puff of sooty smoke—this is the regeneration process in action.

Preventing and managing DPF clogs
Like any filtration system, DPFs can become clogged over time. Regular motorway or high-speed driving helps the filter regenerate effectively. If your driving habits involve short, low-speed trips, consider taking your car on a longer, high-speed journey occasionally to support the DPF's cleaning cycle.

By understanding and maintaining your vehicle’s DPF, you can avoid costly repairs, ensure your car passes its MOT, and contribute to cleaner air for everyone.

Why does my DPF get blocked?​

The problems can occur when you are doing a lot of short local journeys and the car isn’t getting above 40mph for a long enough period to allow the filter to get hot enough to clean itself.

This is why Eden’s experts would never recommend a diesel vehicle for drivers who do mainly local trips and rarely venture outside of town.

How can I fix it?

The best way to prevent a blockage and to keep your DPF running properly is to make sure you occasionally take your car on a run where it can get up to normal temperature and be travelling at more than 40-50mph for a longer period.

This may burn off the soot without the car needing to do anything more, but the engine’s computers may decide they need to help move things along by injecting fuel into the filter. You may notice a change in engine note as this happens. This is nothing to worry about, but the car may flash up a warning if the process is interrupted, for example if you stop driving halfway through the cycle.

What do I do if the light stays on?

If the DPF warning light stays on after you have tried driving for a while, it’s time to call the experts at Eden for advice. We will be able to diagnose the problem, get your car running properly and give you advice to prevent it happening again.

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