Do You Have A Clogged Or Bad DPF Filter?

If your vehicle is running on diesel, you might know the term Diesel Particulate Filter or DPF but you don’t know what that filter does. You also might not know why your vehicle has a faulty or clogged DPF or how you should deal with this issue if you do.

We are going to go over the symptoms of a clogged DPF filter. We will also let you know how important this filter is.

The Signs Of A Clogged DPF Filter

The check engine light is on.
A decrease in engine performance.
Poor fuel consumption.
Have trouble starting your car.
Emitting strange smells.
Damage to the turbocharger.

The Check Engine Light Is On

Check Engine Light

Probably the first sign something is wrong with the DPF, the check engine light will light up on the dashboard. The DPF has sensors to measure the temperature and pressure before and after the filter. If the pressure is not right, the engine control module will light up the check engine light.

If the check engine light is on your dashboard, you must scan the trouble code memory with a code scanner to find out what’s going on.

A Decrease In Engine Performance

If the DPF is blocked or clogged, the exhaust system will be seriously affected. Its ability to remove exhaust from the engine is being disrupted causing a backup in the system.

The backup will cause the engine to run weaker and sluggishly. The more exhaust gases build up, the slower new fuel will be pumped. In turn, you will not be able to accelerate properly. Also, the engine will need more power to push the excess gases out.

Poor Fuel Consumption

Car Fuel Consumption

If the engine is not working correctly, you will burn more fuel than is normal. The problem comes from a blocked filter, causing more fuel to be pumped in order to get the engine running. You will also notice you are not getting the right performance from the engine.

You will end up spending more money on fuel and as the cost of diesel continues to climb, you will definitely notice the difference.

Having Trouble Starting Your Car

A blocked DPF will cause a buildup of exhaust gas in the engine. The gas becomes trapped and cannot get out but will increase pressure which is not normal. It will be difficult to get the engine to turn over. As a matter of fact, the engine will not start until the pressure is released.

This is a safety design for the engine. If the engine cannot start with all this pressure inside, there will be permanent damage to the engine leading to serious repair costs. To ensure this doesn’t happen, clean the DPF regularly to prevent clogging.

Emitting Strange Smells

Car Smells

As exhaust gases build up in the engine, you will notice some strange smells emitting from the engine. Not only is this an issue, but it can also be very dangerous.

The bottom line is, exhaust gases are not safe to breathe in and can also be flammable, putting you and your passengers in harm’s way. Unfortunately, with these smells floating around, it would be very difficult to know if something else is going on.

Damage To The Turbocharger

When the exhaust system is blocked, you have to think about the turbocharger. When the flow of fuel is prevented or slowed down, the temperature can rise very quickly. If this problem is not addressed right away, it will cause the oil inside the turbocharge to carbonize and can be dangerous to the engine.

Where The Diesel Particulate Filter Is Located

Diesel Particulate Filter

The DPF works with the exhaust system. You can find this filter sitting in front of the NOx trap, also known as the NOx storage catalytic converter. You might also find the DPF filter near the exhaust manifold.

It’s usually ahead of the exhaust pipe but can be found behind the first temperature sensor. To remove the filter, you need a screwdriver to remove the surrounding grills and plates. After being removed, there might be some O-rings or other clamps you’ll have to take off.

The Purpose Of The Diesel Particulate Filter

This filter works with the exhaust system by trapping particulate elements, including ash and soot. The DPF is made of a substrate that is made from ceramic material. It has a honeycomb structure that is very effective for trapping debris.

The DPF will hold and store soot from the exhaust so your vehicle can reduce emissions. The soot is burned off from time to time to help regenerate the DPF. During this process, excessive soot is burned off and deposited back into the filter which in turn will reduce the harmful emissions and black smoke you are familiar with from diesel vehicles when accelerating.

These filters are important in order for your vehicle to comply with strict emission standards.

The Cost Of Replacing The DPF

A new diesel particulate filter can be very expensive. This is why it’s important to keep the system running as it should. Instead of replacing the filter, most people will clean it off for a longer life.

As this filter does not normally fail in low-mileage vehicles, it does make more sense to clean it. Quite honestly, a new DPF filter will be more expensive than your vehicle! If properly cared for, you shouldn’t have to clean it more than every 100,000 miles.

How To Clean The DPF

Cleaning DPF


If you take the diesel particulate filter to a professional for cleaning, you might hear the term “thermal method”. This cleaning process is also known as the “bake and blow”. The DPF is placed in an oven and as the heat rises, the soot is oxidized while the airflow pushes ash out of the filter.


This method has proven to be effective. A surfactant surrounds the ash particles making it much easier for water to wash the debris away from the substrate. Once it’s clean it must be completely dried. A special cabinet is required so you will have to wait at least a few hours before it can be reinstalled.

Cleaning At Home

If taking your car to a professional is not on your list, you can try DIY with a special additive. You can find some brands for around £20. These products are used to break down soot and ash.

Here are the instructions found on the back of the bottles.

You will have to place the additive into the fuel tank with the engine running. Once, added, it’s best to drive around for approximately 30 minutes. This will help the additive to circulate in the system and you can drive at any speed you wish, it doesn’t matter. You might also see the warning light go off if it was on before and during the process.

While cleaning additives can break up some clogs, they are usually used for maintenance. If you are using a cleaner every three to six months, you should not experience any clogging issues later on.

If you are still having issues after using an additive, consider engaging one of the professional cleaning methods instead, or better yet, visit your local diesel mechanic for support.

If you are having problems with your DPF filter and you believe it may be clogged you can get your vehicle checked and any issue diagnosed and resolved by booking online today.

For further information on our services you can browse the site or get in touch with us by calling 019253 30468 or you can email us directly at At Lowton Motor Company we service all vehicles produced by all the top manufacturers from the a Ford to a Porsche and everything in between. Our experienced technicians have access to and traning with all the latest technology. You can be sure your vehicle is in safe hands whether it’s in for a repair, a service or just the annual MOT.

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