Can I remove the DPF from my car?

What is a DPF?

A Diesel Particulate Filter is built into a motorcar's exhaust system. It captures harmful soot particulates, preventing them from being expelled into the atmosphere. A Diesel Particulate Filter, therefore, benefits air quality and, by association, public respiratory health.

Reasons for DPF Removal

The main reason for removing a DPF is to save repair costs. The idea is to trick the MoT Tester into thinking that the filter is present, when it is not. Despite making the car unroadworthy, the act of removing and/or disabling anti-pollution features on cars continues to be advertised by businesses.

The activity is so widespread that most major towns and cities in the UK have at least one company promoting DPF removal. These can be found easily, by entering 'dpf removal uk', or 'removal of dpf' into an Internet search engine. The result of the lack of widespread enforcement is an unknown number of vehicles pumping out excessive and unregulated cancer-causing toxins into the atmosphere, all because the car owner wishes to save a few pennies.

Is removing DPFs illegal?

UK legislation says:

“A person who…uses on a road a motor vehicle or trailer which does not comply with such a <construction and use> requirement, or causes or permits a motor vehicle or trailer to be so used, is guilty of an offence.” (Section 42 of the Road Traffic Act, referencing breaches in Construction and Use)

Therefore, using a car on the road that has had its DPF removed is an offence. A car that has had its DPF removed will also fail the MOT Test.

Some garages argue that the act of removing the DPF itself is not an offence. Yet, note Regulation 61. 5(b) of the Road Vehicles (Construction and Use) Regulations 1986:

“No person shall use, or cause or permit to be used, on a road any motor vehicle—

(b)… if the fuel injection equipment, the engine speed governor or any other parts of the engine by which it is propelled have been altered or adjusted so as to increase the emission of smoke…”

In 2024, action was taken by the UK Government against garages that modify exhaust systems, details about which were reported in the motoring press at the time, such as here.

What are the legal alternatives to DPF removal?

DPFs are pretty reliable. If it is blocking, have the underlying cause investigated. Should the DPF be blocked, have it cleaned. If it has been damaged internally, or has melted, it should be replaced.

How much does a DPF replacement cost?

Repair costs depend on the vehicle and your garage's labour rates. Generally, it is more expensive to reinstate a removed DPF than replace one on an unmodified vehicle.

Can I pass an MOT without a DPF?

If your car was not fitted with a DPF from new, then it will not fail on lacking a DPF. If your car possessed a DPF and it has been removed, or modified internally so it does not work, the tester should fail the car. If the tester does not detect that your DPF

has been modified, do not presume that this illegal modification has been sanctioned; a roadside exhaust emissions spot-check is likely to be failed

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