Diesel engines are efficient, but they create sooty particulates in their exhaust that are bad for health. Your Diesel Particulate Filter (DPF) removes the particulates by pushing exhaust gases through a maze of metal channels, collecting the sooty particulates.

Engine management systems are supposed to regenerate the filter unit when needed by applying high temperatures to the collected soot.

For various reasons this regeneration routine can fail (one of the main reasons is when the car is only used for short journeys, never getting fully up to temperature).

When the filter becomes clogged, exhaust flow is blocked. Eventually your engine management will apply a partial shut-down.

The filter is a closed unit, and expensive to replace. It can be cleaned, however, with the right tools and techniques.

If you have an engine management light on, the problem needs to be fixed – even if the light goes off from time to time. The light means the engine is not working properly.

Sometimes, engine management systems will put your car into “limp-home” mode after the fault is detected. That usually doesn’t change till the fault is cleared.

You may be able to get home, but until the problem is fixed your car is not really useable.

Most garages will prefer to simply replace the DPF unit, but this is expensive and rarely necessary.

Fortunately the unit can now be effectively cleaned without removal, at much lower cost.

DPFs usually cost several hundred pounds, even for “pattern” parts. For a branded replacement, fitted in a main dealership, don’t be surprised at a bill of £2500, sometime much more. It’s just not worth it for such dealerships to invest in the equipment needed for DPF cleaning.

With the engine running at 2000 rpm, we apply the cleaning restorer in 3 short bursts, and wait for it to take effect. We then repeat the cleaning process a second time to remove any stubborn carbon remnants.

At that point the vehicle is ready for a road test to make sure the engine’s ability to carry out passive regeneration is restored – that’s what will keep the DPF clean in the future. We’ll also put a cleaning additive into your fuel tank to help with further cleaning as you drive.

Our engineer will explain  how the DPF problem arose so you can avoid it happening again.

In the vast majority of cases it is simply that the car is used for many short runs, so it never gets to proper operating temperature. So at least once a week it’s good idea to let it properly stretch its legs.

There are also additives that can help, and our engineer will explain those.

We do have to warn you, though, that if the car is only used for short runs it is only a matter of time before you see the same warning light appear.

Yes, you do need it. DPFs are a legal requirement – they remove diesel particulates (soot) from the exhaust. None of us wants to be breathing the sooty air that used to come from older diesel engines.

Modern engines with DPFs have actually brought about a very positive change in air quality levels, particularly in cities. 

Your car will also fail its MOT if the DPF is not present, or if it is not working properly.