6 Common Defects which Fail an MOT in Skipton, North Yorkshire

6 Common Defects which Fail an MOT

13 April 2022

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Here at Peter Watson Garage, we want to ensure that your vehicle passes its MOT the first time. With an alarming rise to a combined 2,627,816 vehicle failures from the 1st January - 31st December 2021, a total of 7.9% of all vehicles, we have put together a comprehensive list of common defects so you can look to keep your vehicle well maintained throughout the year, ahead of your MOT. You might be surprised to hear that the majority of vehicles fail an MOT for very small issues which could easily be avoided before the test.

Defects are usually categorised into four groups, but you need to take all of them seriously if you wish to pass your MOT and avoid costly repairs down the road. Let’s take a look. 

Categories of defects 

1. Dangerous defects: A car with a dangerous defect cannot be driven under any circumstances, including to an MOT test centre or repair garage.

2. Major defects: This would still result in an MOT failure, but providing that your old MOT certificate was still valid you can still drive your vehicle. If this has expired, the vehicle can only be driven to a repairs workshop and you must have proof of your appointment to show to the police in case you are pulled over.

3. Minor defects: This would not cause you to fail your MOT. Whilst they are not serious enough to substantiate an immediate repair and re test, the government still would advise that you do so.

4. Advisories - this is used to identify parts that will likely need repairs in the future and what category of seriousness as a defect this would fall into.

Lights & Visibility 

Collectively your lights and visibility accounts for 35% of all defects for MOT’s. With an increasing dependence on electrical systems, it is easy to see why. This can include anything from electrical wiring, if the lenses on your lights have become foggy, your reflectors do not emit sufficient light, or even just a blown bulb. Typically, we look at your field of vision, what condition your glass is in and in your rear view mirrors, as well as the effectiveness of your wipers and washers.

Brakes and suspension

Accounting for 34.1% of issues, brakes and suspension can be a minefield to navigate. You have everything from disc or pad issues, whereby pads on either side of the disc on your drive wheel wear over time. This can lead to more permanent defects such scored brake discs, which would lead to a replacement disc as well. If one side were to wear quicker, this can also lead to uneven driving under braking. Unsurprisingly due to a large number of potholes and uneven surfaces on Britain’s roads, your vehicle's suspension system will doubtless be taking the brunt of bumps and dips which can lead to broken springs and worn suspension joint amongst other things.


Your tyres can lose tread faster by using the wrong type of tyre for your vehicle and the driving conditions i.e., winter tyre in summer and vice versa. Constantly in contact with the road and affected by changeable British weather, tyres accounted for 11.6% of issues. Here we check for sufficient air pressure, tread depth, as well as any damage to the tyres.

Emissions and fluid checks

In line with carbon reduction, your car needs to be checked for CO2 levels amongst other harmful gases. Aside from benefiting the environment, leaking exhaust gases can be dangerous for your health. We can add additives to your fuel tank which travels through to your exhaust pipes reducing carbon along the way. The other most common type of fluid tests are your power steering fluid and brake fluid, which also has to meet the required level. Out of all checks with regards to fluids however, an oil or fluid leak that creates a 75mm diameter pool on the floor will guarantee you a major fail on your MOT.

Damage to the windows or number plate

Windscreen cracks larger than 10mm in diameter in your field of vision or 40mm in diameter anywhere else would constitute a major failure to your MOT. Smaller cracks may be classed as minor faults, again depending on the severity. Your windows also may be marked down due to tinting, scratching, and discolouration. Any unreadable front or rear number plates immediately constitute a failed MOT as this prohibits the police from being able to identify your vehicle.

Internal safety

Last, but definitely not least are seat belts and airbags. Seat belts must be able to retract, airbags have to be in place, and no warning lights pertaining to your airbag in order to avoid a failed MOT.

There we have it, the 6 most common defects that fail an MOT. If you need to book an MOT for your vehicle or have any questions or concerns, please get in contact with us today.

Note - percentages of defects taken from Q2 of 2019 which means a larger percentage today based on failed MOT’s in the year of 2021.

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