We use cookies to give you the best possible experience. You refine the data you’re happy for us to track. By using our site, you agree to our Privacy Policy

Your Privacy

When you visit any web site, it may store or retrieve information on your browser, mostly in the form of cookies. This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The information does not usually directly identify you, but it can give you a more personalised web experience.
Because we respect your right to privacy, you can choose not to allow some types of cookies. Click on the different category headings to find out more and change our default settings. However, blocking some types of cookies may impact your experience of the site and the services we are able to offer.

Strictly Necessary Cookies


Necessary cookies are absolutely essential for our website to function properly. These cookies ensure basic functionalities and security features of our website, anonymously.

The site needs these cookies

Analytical/Performance Cookies

Analytical cookies help us to understand how visitors interact with the website. These cookies help us to provide information on metrics the number of visitors, bounce rate, traffic source, etc.

Performance cookies are used to understand and analyze the key performance indexes of the website which helps us to deliver a better browsing and user experience for the visitors.


Advertisement cookies help us decide which products, services and offers may be relevant for you. We use this data to customise the marketing content you see on websites, apps and social media. They also help us understand the performance of our marketing activities. These cookies are set by us or our carefully-selected third parties.
DPF banner

What is a DPF or OPF exhaust?

A guide from bravoauto to DPF and OPF systems.

What is a DPF or OPF?

DPFs are found in diesel engine cars and stands for Diesel Particulate Filter. OPFs are found in petrol engine cars built since September 2018 and stand for Otto Particulate Filter. These systems work in very similar ways and are part of the exhaust. They force the exhaust emissions through the filter which then captures many of the harmful emissions produced by the engine. In this guide we’ll discuss both systems in more detail. 

How do they work?

DPFs and OPFs are part of the exhaust system of diesel and petrol cars. From the outside they appear as metal cylinders attached to the exhaust. However, on the inside of these filters there is a fine mesh which collects particulate emissions produced by the engine before they are released into the environment. The filter burns these particulates into arguably less harmful gases which are then passed through the exhaust and into the atmosphere. 
DPF filter on used bravoauto car

bravoauto technician completing 150 point safety check on used car

Why are they needed?

The filters are needed to help reduce the harmful particulates and emissions that are created from burning fuel. The emissions produced such as carbon dioxide contribute to global warming and the particulates such as soot contribute to poor air quality and have been linked to health issues such as asthma. 

Exhaust filters such as DPFs and OPFs greatly reduce the particulates emitted into the environment which helps keep the air cleaner and reduce the negative impact of burning fossil fuels.

Is DPF failure common?

Many people think that DPFs can reduce reliability of diesel cars and are prone to failure. However, these components are engineered to last with the correct use.

DPFs need to hot to allow for the particulates to burn off and keep the DPF clear. If you have a diesel car and only do short trips this prevents the engine reaching its ideal operating temperature. As a result, the engine produces more soot and the DPF does not warm up enough to burn off soot captured. If you regularly do short journeys this can then cause the DPF to clog.

To look after the DPF go for a long drive every 1,000 miles which will allow everything to heat up enough to clear the filters. Many cars can also run a regeneration cycle which manually burns off the DPF to clear it.

If you frequently do long journeys, you are unlikely to have a problem with the DPF. OPFs are not as prone to clogging up because petrol engines warm up quicker and run at higher temperatures which allows the OPF to clear.

DPF exhaust on car

bravoauto car driving along the road

The benefits and compromises of DPFs and OPFs

DPFs and OPFs do not reduce performance or increase fuel consumption. Instead, the computer controlling the car’s functions may reduce the amount of power produced to compensate for the filter. This is to ensure that fuel economy is not reduced. 

DPFs and OPFs can reduce the noise emitted by the exhaust which for most cars is another positive of these systems. However, for a few cars such as high-performance models, enthusiasts may miss the added noise of exhausts without OPFs fitted. 

The benefits of DPFs and OPFs to the environment far outweigh any possible drawbacks.