Tighter MOT testing for diesel exhaust filters announced

Roads minister Robert Goodwill announces tougher tests in response to drivers removing particulate filters

MOT testing for diesel vehicles is to become stricter from February next year, the Department for Transport (DfT) announced this week (December 4).

Under the regulations, garages will be required to check for a diesel particulate filter (DPF) in the inspection of the exhaust system if one had been originally fitted as standard.

Tighter MOT testing for diesel particulate filters are set to come into force

Soot build-up in the filters, which can affect vehicle performance, leads some drivers opting to remove the filter, making cars illegal for road use.

Some firms offer services to remove the filter, claiming it will improve the vehicle’s fuel economy.

However, it is an offence to drive a vehicle that has been modified this way, as it will no longer meet the emissions standards the car achieved when it was approved for sale in the UK.

But the regulations now mean that vehicles will automatically fail the MOT test if the filter had been fitted as standard but is found to be no longer present.

The filter works by trapping solid particulate matter from exhaust gases. This type of filter has been in use for more than 20 years and helps meet European emission standards for air quality.

According to DfT guidance, the filters need to be ‘regenerated’ regularly through burning the soot to gas at a very high temperature, leaving behind a residue. If this is not carried out properly, howver, regeneration can lead to a build-up of soot, which can affect performance.

Roads minister Robert Goodwill said: “I am very concerned that vehicles are being modified in a way that is clearly detrimental to people’s health and undoes the hard work car manufacturers have taken to improve emissions standards. It has become apparent the government had to intervene to clarify the position on particulate filter removal given the unacceptable negative impact on air quality.

“This change to the MOT tests makes it clear — if you have this filter removed from your car it will fail the test.”

Simon Birkett, founder and director of Clean Air in London, has previously been critical of the UK government with regards to enforcing effective DPF checks (see airqualitynews.com story).

Commenting on the DfT announcement this week, he said: “This is excellent news that will help protect public health and honest motorists worried about buying a second-hand diesel vehicle that might be illegal to drive.

He added: “This is a timely reminder of the importance of fully operational diesel particulate filters and emissions control systems and the need for the final Trilogue meeting next Monday to ensure the new regulation of the European Parliament and of the Council on periodic roadworthiness tests for motor vehicles and their trailers includes the effective, independent and periodic tailpipe testing of oxides of nitrogen (petrol and diesel vehicles) and particulates (diesel vehicles only)

“Europe should keep its current legislation rather than approve a new regime that would weaken again emission systems checks.”