21% decrease in MOT fails due to exhaust issues despite stricter diesel tests

New data from Protyre reveals a 21 per cent year-on-year decrease in the proportion of MOT test fails that resulted from failed exhausts in the year since the DVSA introduced one of the largest-ever changes to the test on 20th May 2018 with stricter regulations on emissions from diesel cars. Protyre is the UK’s fastest growing supplier and fitter of tyres and automotive services with 150 nationwide garages.

Further analysis from Protyre also shows that only 7 per cent of diesel vehicles that failed their MOT did so because of issues with the exhaust – compared to 11 per cent of all vehicles overall that failed their MOT because of exhaust issues. These new figures come despite overall increases in the raw number of MOT tests that failed because of exhaust issues shown in the most up-to-date DVSA figures.

Protyre’s national retail operations manager, David Sholicar, comments: “The fall in the proportion of MOT fails attributed to exhaust issues at first appears surprising as the new MOT test includes stricter regulations on emissions from diesel cars. The test changes also mean that it is now law that any car with a diesel particulate filter automatically fails its MOT if smoke is visible from its exhaust.”

Sholicar continues, “One reason for this reduction is down to the reduced popularity of diesel cars and nationwide year-on-year decreases in sales of new diesel vehicles in recent years of up to 20 per cent. However, the data also shows that the decreased proportion of MOT fails (despite an overall increase in numbers) is likely down to stricter criteria on other components.”

Protyre’s data shows a 7 per cent year-on-year increase in the proportion of MOT tests that failed because of warning lights and a 7 per cent year-on-year decrease in the proportion fails because of faulty brakes. The proportion of MOT fails attributed to failed suspensions decreased 11 per cent and the proportion attributed to faulty car lamps also decreased 8 per cent. The new MOT test includes new testable items related to braking device performance, the daytime running of lamps and the Engine Malfunction Indicator Lamp (or Check Engine Light).

In the year since the changes to the MOT test, faulty suspension was the most common reason for a test fail, followed by brakes, lamps, tyres and obstructions to drivers’ view of the road.