MOT emissions failures rise following exhaust test changes

Over 740,000 cars have failed their MOT test after tougher checks on exhaust emissions were brought in earlier this year (May), the government’s vehicle standards agency has claimed.

According to DVSA as many as 238,971 diesel cars and 505,721 petrol cars have been taken off the road or fixed as a result of the new, tougher testing requirements, which are aimed at tackling air pollution.

Diesel cars emit particulates in the form of soot

This compares to 350,472 cars failing the emissions test during the same period in 2017.

Changes to the MOT test brought in in May affect the way that cars, vans, and other light passenger vehicles are tested, and see defects categorised as either ‘dangerous’, ‘major’ or ‘minor’ depending on the type of issue found.


Under the new system, MOT testers are required to test vehicles to the manufacturer’s plate value — the emission limit specified by the car maker — or using new default limits set by the Driver and Vehicle Standards Agency (DVSA).

Vehicles are given a ‘major’ fault — meaning that the vehicle fails its test — if the MOT tester is able to see smoke ‘of any colour’ coming from the vehicle’s exhaust. Cars also fail the MOT if the tester can find evidence that the DPF has been tampered with.

Gareth Llewellyn, Driver and Vehicle Standards Agency (DVSA) Chief Executive, said: “DVSA’s priority is to protect everyone from unsafe vehicles and drivers.

“We are committed to making a real difference to those in society whose lives and health are blighted by poor air quality.

“Since introducing the new tighter MOT emissions test in May, nearly 750,000 vehicles have been taken off the road or fixed.”

Related Links
DVSA — Diesel vehicle emissions limits

[Story amended 27/11/2018 to reflect that figures related to number of vehicles failing MOT emissions test since introduction in May 2018]


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