BMW 520 D exhaust

We have a problem with our car’s diesel particulate filter DPF- can your garage help?


Most car owners have a basic understanding about how certain components on the car works, like the car’s brakes for example. However, with that said, a lot of car owners will not know what the “DPF system” does on their car or how it can sometimes go wrong and fail to regenerate.

This is with good reason why a lot of car owners will not have the foggiest idea what a DPF system does or how it works, as it’s a part you might have not known was fitted to your car, until it goes wrong. In a nutshell the DPF system forms part of your car’s exhaust system, and it helps to reduce emissions for diesel cars.

Within this article we are going to explain what the cars diesel particulate filter is in more detail, and also how our garage can fix DPF problems which may persist with your vehicle.

What’s is a diesel particulate filter DPF?

So, first things first, a lot of car owners might think that the car’s exhaust system might just be a tubular piece of steel and its only function is to remove and direct exhaust gases away from the engine.

However, with more modern vehicles, most exhausts are fitted with a DPF, diesel particulate filters as part of the exhaust, so gone are the days where the exhaust was just a steel pipe with a back-box silencer.

In relatively simple terms, it is the DPF’s job to make the car more environmentally friendly by removing soot that is created when burning diesel fuels.

Therefore, your car may  have a relatively complex sort of filter, which helps to remove the diesel soot and diesel particulate that would otherwise just escape through the exhaust into the atmosphere.

As you can imagine with any sort of filter, it can become clogged, this is when car owners often need a qualified mechanic to rectify the DPF problem, either through cleaning the DPF or sometimes the whole DPF system will need to be replaced. That’s of course if the car fails to regenerate itself, as sometimes the car’s ECU will just send a message, and may sometime be able to just regenerate itself.


“Most cars will have a system in place, whereby the ECU, that the electronic control unit can kick in to start the process which is called regeneration”.


Regeneration is a system which is used on some cars, whereby extra fuel (diesel) is used to raise the exhaust temperature and the point of this process is to burn soot away from the exhaust which can help to lessen the build up of soot caused by burning diesel in the engine.

However, what can sometimes occur, on some vehicles is that the car “fails to regenerate”, and sometimes goes into a constant cycle of regeneration, which is obviously when a qualified mechanic is needed to rectify the problem as the regeneration is failing.

On some vehicles you may therefore see on the car’s dashboard, a warning message that “regeneration has failed” or there is a “DPF has a problem”, which is when a qualified mechanic is needed.

What should I do if my vehicle fails to regenerate?

If your vehicle fails to regenerate, then it can mean sometimes that the car enters a limp home mode, which means that you will have limited power from the engine.

What type of driving do mechanics think contributes to a DPF becoming clogged?

DPF problems can occur on any car were a DPF system is fitted, that’s to say it can even sometimes occur at any time.

However, a lot of mechanics share the view that DPF’s can sometimes become clogged faster when the driver is doing a lot of short driving at relatively low speeds.

Therefore, if you are a driver that drives relatively short commutes, and at relatively low speeds for example, for example you are regularly stuck in rush-hour traffic in Cardiff that’s to and from work, then this type of driving can sometimes mean that the DPF will become more regularly clogged.

Shouldn’t my car just be able to regenerate itself without the need of a mechanic?

It is fair to say that a car can undergo “passive regeneration” or “active regeneration”, however sometimes the DPF can become so clogged with diesel particulate that sometimes the car will fail to regenerate itself, and this is when a garage and qualified mechanics are needed.

My engine management light is lit could it be the DPF?

A lot of vehicles are brought to us with the DPF warning lights on, our mechanics will be able to quickly look at your cars fault codes and to analyse the severity of the DPF problems.

For example, sometimes it can be a problem with the cars EGR system, that’s the exhaust gas recirculation system, and this is a more complex problem, however sometimes the car will just need to be regenerated after cleaning the DPF problem, so even though a car’s dashboard just says “DPF Failure” or “DPF Problem” there might be more problems that need fixing than just to clean the DPF, for example it could be as mentioned the cars EGR system at fault also.

As each cars DPF will have a different level of being obstructed or clogged, our mechanics will need to assess the best course of action when they have looked at your car’s exhaust system and read the relative fault codes that are being presented from the cars electronic control unit (ECU).

My car has a problem with the EGR, exhaust gas recirculation system can garage help?

Some cars will also have EGR problems, that is problems with the car’s exhaust gas recirculation system, therefore it might not be a relatively straight forward to fix in terms of just clearing the cars DPF, sometimes there will be several problems that may occur and the cars EGR might be one of the problems that needs to be rectified with some vehicles.

Could my car fail its MOT because of DPF problem?

Car owners will be aware that their car can fail an MOT for a number of reasons, for example a slack handbrake or for example the car’s headlights might not be working properly, however a lot of car owners might not be aware that the car can also fail because of problems with the DPF system which means that the car may fail its emissions test.

Therefore, if your car fails its emissions test it might be a problem with the diesel particulate filter, our garage can help to rectify such problems with your vehicle, and also to prepare your car ready for its MOT or its MOT reinspection.

Is it expensive to replace the DPF system completely?

Yes, in a nutshell the cars DPF is a relatively expensive component that is fitted to your car, this will obviously vary greatly in price depending on the manufacturer and the model of your vehicle.

However when a car owner first hears that they have a DPF problem with their vehicle, they immediately think that sometimes it may be better to replace this component completely.

However, what you have to be aware of as a car owner, is that the DPF is often an expensive component, therefore it is not like say the car’s brake discs or pads, which are relatively inexpensive in comparison, instead the DPF can often be a very expensive car part, and this is often why a garage owner and mechanics will try to often clean the DPF if it is possible to do so, rather than replacing it, however sometimes you might be left with no other option but to completely replace the cars DPF system.

How motorway driving can sometimes help:

Now you may have read online, that driving your car regularly on the motorway can sometimes help to extend the life of your cars DPF sometimes, and it is the view of a lot of mechanics share, that is the car’s DPF is much more likely to become clogged if you travel shorter and slower speed commutes.

However, even if you are a regular motorway commuter it is still possible that your cars DPF becomes clogged, that’s because if the car has a DPF then it can become clogged as any time.

How our garage can help:

Our garage and mechanics are located in Cardiff, South Wales, we can help to rectify any DPF problems that your car might have.

We work on a wide range of different cars, that are made by a wide range of different car manufacturers.

For example, we can be changing or repairing the DPF on mass produced saloon car, yet we can also change the DPF on high-performance and also executive diesel cars, we therefore work on a wide range of cars while also offer very competitive prices.

We don’t just repair DPF’s, we can also offer to repair any make or model car, we can also offer car servicing and car repair such as changing your car’s brake disc, brake pads, exhaust system, car battery, cambelts can also offer many different servicing options such as full car servicing,  interim car servicing and also to change your car’s engine oil and oil filter.

To arrange for your car to be viewed by our mechanics then why not give us a ring today?





0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply