Diesel particulate filter check required as part of MOT test from February 2014
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
The Department for Transport (DfT) announced on Wednesday that tests for diesel cars and lorries are to be tightened up to ensure vehicles have a critical exhaust filter if one had originally been fitted as standard, Roads Minister Robert Goodwill has announced. The full announcement can be seen at:
Garages and testing stations will be required check for a diesel particulate filter (DPF) in the inspection of the exhaust system as part of the MOT test (or annual test for heavy vehicles) from February 2014.
The vehicle 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, improving air quality and health standards.
Some firms offer services to remove the filter, claiming it will boost consumption. But 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.
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.”
The filters need to be ‘regenerated’ regularly through burning the soot to gas at a very high temperature, leaving behind a residue. If not carried out properly, regeneration can lead to a build up of soot, which can affect performance. This has led to some diesel vehicle owners opting to remove the filter, which makes their car illegal for road use.
More information can be found via the ‘Diesel particulate filters guidance note which will be updated to reflect the changes to the MOT test.
Simon Birkett, Founder and Director of Clean Air in London, said:
“This is excellent news that should help protect public health and honest motorists worried about buying a second-hand diesel vehicle that might be illegal to drive.
“We need to be sure though that the Minister’s strong words are backed by an effective MOT test not a simple visual check that might fail to spot the common practice of replacing diesel particulate filters with shiny but empty casings.
“The Government’s announcement 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.”
1. Ash is a standard by-product of the combustion process that takes place in diesel engines. However, unlike soot, the ash that accumulates in filters cannot be burned off by regeneration processes (or by chemical cleaners added to the fuel tank) and requires periodic cleaning in order to maintain the efficient operation of the filter and the engine.
2. Ceramex, for example, offers a nationwide diesel particulate filter cleaning service for cars and light commercial vehicles in partnership with Unipart Automotive and the Parts Alliance. Details at:
3. Other articles by Clean Air in London about diesel exhaust