Ministers to consider action on diesel filters

A government minister has confirmed that officials are considering ways to toughen vehicle regulations to prevent the removal of diesel particulate filters from cars.

A diesel particulate filter (DPF) captures and stores exhaust soot in order to reduce emissions from diesel cars, and is legally required to prevent the emission of high levels of particulates.

Diesel cars emit particulates in the form of soot

The filters have a finite capacity, which means that trapped soot has to be emptied or ‘burned off’ regularly to regenerate the DPF.

The regeneration process cleanly burns off the excess soot deposited in the filter at high temperature, reducing the exhaust emissions.

But, soot build-up in the filters can affect vehicle performance, especially if the vehicle is mainly used to make short journeys at low speeds, and leads some drivers to opt to remove the filter.

Under the Road Vehicles (Construction and Use) Regulations (Regulation 61a(3)) using a vehicle which has had its DPF removed is an offence and can incur a fine of up to £1,000 for a car or £2,500 for a light goods vehicle.


Rules were tightened in 2014 to require garages to perform a visual inspection of filters as part of the MOT process. This means that a vehicle will automatically fail its MOT test if the filter had been fitted as standard but is found to be no longer present.

The Driver & Vehicle Standards Agency (DVSA) has claimed that as many as 1,800 vehicle users have been caught operating without a DPF since the MOT testing requirements have changed.

However, recent reports have suggested that the number of vehicles operating without a filter is significantly higher, leading some to claim that more stringent testing is required to ensure that DPFs are present on all diesel vehicles.

Concerns have also been raised that it is not an offence for companies to offer services to remove diesel particulate filters (see story).


The issue was raised in Parliament this week by the Liberal Democrat Peer Baroness Randerson, who questioned the Department for Transport as to whether steps are being taken to bring forward legislation to make it illegal for a garage to remove a pollution filter from a diesel vehicle.

In a written response, Department for Transport Minister Baroness Sugg confirmed that officials are seeking to tighten the existing rules to prevent the removal of diesel filters.

She wrote: “It is an offence under the Road Vehicles (Construction and Use) Regulations (Regulation 61a(3)) to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet. Removal of a Diesel Particulate Filter (DPF) will almost invariably result in a contravention of the Regulations, making the vehicle illegal to use on the road.

“The Department for Transport’s officials are considering ways to develop these regulations further in order to ensure that anyone caught flouting the rules, or advertising services to circumvent the law, are brought before the courts.”


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