The Diesel Particulate Filter (DPF)

November 17, 2020


With advancements in medical science and technology came the ability to detect certain cancers and illnesses and trace the possible cause.  A great deal of this research heavily correlated cancers, respiratory issues and many other health troubles with the exhaust products of both DIESEL and PETROL internal combustion engines. With our world today so heavily reliant on all forms of engines in industry, domestic and economic contexts banning the internal combustion style engine was not an option, so restrictions were set in place to limit the toxic gases and particulates that they emit.

On a Diesel Engines Exhaust Aftertreatment system these components include the:

Exhaust Gas Recirculation Circuit: ( EGR)

Diesel Oxidisation Cat ( DOC )

Diesel Particulate Filter ( DPF)

Selective Catalytic Reducer (SCR) – Functions with the use of the ADBLUE you may of noticed at certain service stations.

On a Petrol engine exhaust aftertreatment system components found can include:

Exhaust Gas Recirculation ( EGR)

Catalytic Converters ( CAT Convertor)

Petrol Particulate Filter (PPF) – Fairly new to the automotive market.

Each of the above parts need in depth explanation on what they do, how they work issues that they can cause the owner and how to maintain the engine to avoid costly failures. For this reason before the reader glazes over we will write detailed explanations over the coming months firstly kicking off with the most controversial, talked about and to some trouble making component the DIESEL PARTICULATE FILTER (DPF).

What Is a DPF?

A Diesel Particulate Filter (DPF) is a filter incorporated with a diesel, (and now some petrol engines, Petrol Particulate Filter (PPF) ) exhaust system. Its job is to trap and store any solid particulate matter created from an internal combustion engine before it is released out of the exhaust tail pipe or stack. Pre Particulate filters, this particles would settle in our environment and eventually can cause health issue due to exposure, ingestion and or inhalation.

What does a particulate filter look like & How can I Identify if my vehicle has a Particulate Filter

A Particulate filter looks like a big steel muffler but what makes it different than a muffler is you’ll see electrical wiring routing to exhaust temperature sensors and rigid steel tubing routing around it that is used for monitoring of the exhaust pressure to calculate the restriction of exhaust flow through the filter due to build-up of particulates.

The temperature sensors and the tubing that eventually routes to a pressure sensor are constantly sending information to the Engines control module. What is being done with this information will be discussed down the track.

Some Particulate filters are underneath the vehicle installed inline as part of the exhaust system and some will be harder to find and can be tucked in between the engine and firewall of the engine bay or neatly hidden somewhere else within the bay depending on manufacturer.

The harder they are to see the harder they are to remove (a point worth factoring in if purchasing a high km modern diesel).

A quick and easy way to identify if your Diesel vehicle has a particulate filter is if it was manufactured post 2015 the chances are you have one or if the vehicle is European and built from 2005 onwards you more than likely will have a DPF.

Europe leads the way in strict emission laws hence you’ll find emission components much earlier on any vehicle imported from Europe.

What’s Inside A DPF?

These articles are designed to give someone who’s never heard of a DPF a quick insight. We won’t get too technical with what you’ll find inside a DPF.

Hundreds of variances our found. Simply if you cut one open on most occasions on the inlet of the filter, (apart from a sooty black mess) you’ll find a Diesel Oxidisation Cat (DOC). This is a diesels version of a catalytic convertor and looks like a fly screen.

After the flyscreen style square material, you will find a chess board style honeycomb pattern that runs the majority of the length of the filter. This is the Particulate filter and responsible for trapping the particles. It’s made of a ‘Silicone Carbide’ material.

This material can easily be damaged if an inexperienced person attempts to clean a DPF with the wrong chemicals or equipment, for example a ‘high pressure washer’).

Can’t I just remove the DPF?


Apart from it being highly illegal with the consequences including big fines and your vehicle being defected until all deleted parts and software restored, there’s hundreds of valid reasons why not to remove your DPF. These include:

Warranties- removing your vehicles DPF is an easy way to void your warranty.

Environmental- these components have been put in place to prevent our air quality/ environment and to reduce health issues associated to pollution from exhaust fumes.

Ethical- Less toxic particles settling on our food sources, running into our drinking water catchments and floating through the air reduces yourself, your families and your friends chances of getting seriously ill. (Don’t be selfish)


The more particles your engine creates the quicker your DPF or PPF will load up. When the pressure sensors indicate to the ECM the DPF is full the vehicle will perform a regeneration.

To successfully conduct this, certain conditions must be met. These conditions are hard to accommodate in short trips & extended idle city driving. For this reason your DPF will fail.

Don’t worry if you’re getting told you need to replace the DPF get a second opinion from a specialist. In most cases a DPF can be cleaned for the fraction of the cost of a new unit.

If you ignore the signs of a restricted DPF or your mechanic is constantly forcing burns you’ll damage the DPF beyond a serviceable state.


– Service your engine

– If doing home oil + filter change’s ensure correct spec oil is being used.

– Use a workshop/mechanic with specific knowledge of vehicles with modern exhaust aftertreatment systems. knowledge

– Use a Quality Fuel additive such as FTC Decarbonizer

– Be Aware of driving habits – Get out on a free way for a good run every 250kms or so if you’ve been doing short trips with stop start conditions. If your consistently doing short trips get in contact to organise removal and proper off vehicle cleaning/regeneration to your DPF.

– Contact us for advice.

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