Vehicles failing MOT in record numbers over emissions

Failures up by more than 70 per cent last year compared to 2017/18 levels

Vehicles failing MOT in record numbers over emissions
Image: Bigstock.

Almost 1.3 million vehicles failed their MOT last year because of faults relating to exhaust emissions, new data suggests.

A Freedom of Information (FOI) request to the DVSA found more cars have failed on emissions in the past two years than any other before it.

Diesel vehicles have seen the greatest surge in failures due to emissions, with a rise of 240 per cent compared to just 37 per cent for petrol vehicles, has reported following its FOI request.

In May 2018, the government introduced tougher MOT regulations to clamp down on vehicles producing excessive emissions which led to a significant rise in failures.

Related: Police issue warning amid lockdown MOT confusion

Jessica Potts, head of marketing at, said: “The regulations have mostly impacted diesel cars, causing more than triple the number to fail, compared to petrol car failures which have only increased by a third.”

Recent changes to rules for cars equipped with a DPF triggered the increase.

Vehicles with DPFs that show evidence of tampering or if smoke of any colour can be seen coming from the exhaust will now fail the test.

The DVSA also introduced new fault categories, with ‘major’ or ‘dangerous’ faults resulting in a failed test.

Almost all petrol emissions failures were classed as ‘major’ last year.

Related: New MOT testing service smartphone app meets mixed response

Around five per cent of all diesel emissions failures were classed as ‘dangerous’.

Jessica added: “An increasing number of relatively modern diesels are struggling to pass the MOT test as their emissions control systems face tougher scrutiny.

“It’s important these systems function correctly to protect the environment but putting them right can also cost owners thousands of pounds.”

Despite diesel failure rate increases in recent years, petrol cars are still more likely to fail, with 4.5 per cent of the total number licenced failing annually due to emissions, compared to 3.3 per cent for diesels.

Related: Fourmative makes MOT quality control check sheet available for GW readers

Home Page Forums Vehicles failing MOT in record numbers over emissions

Viewing 10 posts - 1 through 10 (of 10 total)
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  • #207384 Reply

    Almost 1.3 million vehicles failed their MOT last year because of faults relating to exhaust emissions, new data suggests. A Freedom of Information (F
    [See the full post at: Vehicles failing MOT in record numbers over emissions]

    #207389 Reply
    Alan Sutor

    Hardly a surprise is it – they started testing diesel cars to the homologation value which is, in most cases, significantly lower than the legal limit for when that vehicle was built. We are effectively testing to a ‘brand new’ standard on this aspect. Imagine if we failed every car which didn’t have brand new tyres fitted? There would be uproar but here we are doing it for diesel emissions.

    #207392 Reply

    We have little experience of this increase .
    We recommend customers to take their car for a 10 mile drive before coming in for an MOT providing it is legal to do so. We make sure the engine is at full operating temperature before testing.
    This seems to avoid the hassle of failures where there is no real fault.

    #207394 Reply

    Local garage do repairs in morning mot in afternoon.

    Every time is cold and not fully warm, so book for pm test, rag down road
    Third gear 3000 rpm first

    #207396 Reply

    Personally I blame our mot tester Eddie Hitler. He probably failed every single one himself?

    #207397 Reply

    Perhaps “Eddie Hitler” got confused and put the probe up the wrong bottom, and got emissions reading from something else!

    #207400 Reply

    This is good news, MOT test standards are being adhered to and people who shouldnt have a diesel will get a vehicle more suited to their needs. Doing shopping once a week in a diesel is never going to end well and emissions failing is a good tell tale of this. Sooner there are more BEVs on the road, the better.

    #207401 Reply

    Craig, buddy.

    How is that? Some of these electric cars, parts are once only
    So you have to order new parts to come from other side of the world.

    You crash one and catches fire, hard to putout.

    Did see an amusing Tweet two transit vans, 3 months old recovered in
    Due to blocked dpf only doing 2 miles a day

    #207393 Reply
    Neil Skuse

    The biggest issue we find is Diesel Vehicles are pottering around town and just building up carbon in the exhaust system and when they are in for MOT are failing badly.We are having to carry out numerous carbon cleans to pass the levels required.

    #207834 Reply

    Carry out lots of carbon cleaning is going to pump out more in that test than what driver does in a year.

    Had car in the other day, gulf IV tdi
    Was testing what V max in 1st gear was, exhaust was full of neat diesel
    Smoking like hell

Viewing 10 posts - 1 through 10 (of 10 total)


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