Why Cars Fail MOT’s [Infographic]

Why Cars Fail MOT’s [Infographic]

Have you ever thought about what the most common things that vehicles fail their MOTs for? Is your car or van’s MOT test on the horizon? If so, you may be feeling somewhat nervous. Many people feel stressed when taking their vehicle for the test, with the cost of any necessary repairs a big concern. Strikingly, as many as 40% of cars and 50% of vans fail their MOTs in Barnsley and Wombwell, leaving drivers without a roadworthy vehicle and facing unwelcome bills for repair work. Read on to find out the most common reasons why vehicles fail their MOTs. 

Why Do Cars Fail Their MOT


The most common reasons for MOT failures


17% of all MOT failures are due to an issue with lights. Often, this might be a simple case of a blown bulb. To make sure your car’s lights are in order before the test, switch on all your lights and walk around it to check they’re working properly. You should ask a friend to stand behind the car as you press the brake pedal – the brake lights should light up accordingly. 

You should also check that the indicators are flashing correctly and that your number plate lights are in full working order. Assess the condition of the lights – there should be no cracks in them or other damage.


Your car’s tyres are the only components that make physical contact with the road. Therefore, it’s important that they’re checked regularly throughout the year to ensure they’re in good condition. Using a 20p piece, check their tread depth across the width and all the way around. If the outer part of the coin can be seen, it’s very possible that your tyres are below the legal limit. 

A tread depth under 1.6mm will cause your car to fail its MOT test. As well as assessing your tyres visibly, you should also feel inside the tyre to check for uneven wear. If you notice signs of uneven wear, it’s possible your car has alignment issues or your tyres are underinflated. 

Look out for any lumps or cuts too. Both of these can cause problems on the road, potentially even resulting in a dangerous blowout. They should be fixed as quickly as possible. Lastly, you should check the tyres are right for your car. As well as making sure they’re the same size across each axle, you should also ensure they have a suitable speed rating. Problems with tyres account for up to 14% of MOT failures. 

Registration plate 

You may not think that there’s much that can go wrong with your car’s registration plates. However, they’re actually responsible for 14% of MOT failures. Check both your front and back plates for excessive damage or deterioration. If either of them has become damaged in a crash or become worn and hard to read over time, you must replace it before your MOT test. Not doing so could result in a failure. You should also make sure the registration plate light is in full working order. 

Windscreen and wipers

Problems with the windscreen and wipers are the reason for up to 12% of MOT failures. Wipers that either smear the screen or which are visibly damaged will cause your car to fail its test. 

Cracks or chips in your windscreen which obscure your view of the road will also lead to an MOT failure. There must be no damage in zone ‘A’ of over 10mm in diameter and no damage in the rest of the windscreen’s swept area of more than 40mm. There should also be no damage to the windows on either side of the driver’s seat. Both the windscreen and windows should be free from excessive tinting or any discolouration.


With 7% of MOTs in Barnsley and Wombell failing due to issues with the brakes, it’s important to check this important component before the test. As well as visibly inspecting the discs and pads (you may need to take the wheel off to do this) for wear, you should also listen out for any unusual noises when driving the car. Do you hear grinding or squealing sounds? If so, this is a good sign your pads are too low. 

Many cars fail their MOT due to handbrake issues too, with many requiring adjustment to pass their tests. To see if your handbrake needs tweaking, stop your car on a steep slope and then apply it. If it doesn’t hold the car, that’s a good sign that it’s not working as it should.

Exhaust system

The exhaust system is responsible for 7% of all MOT failures, so it really is worth making sure yours is in full working order before your car is tested. The system mustn’t have any serious leaks or corrosion, and it must also be securely fixed to the vehicle using either exhaust mounts or rubber fitting mounts. It should also have the required number of silencers for your car’s specific make and model. Your vehicle may fail its MOT test if the noise levels it produces are deemed excessive. 


Worn suspension systems account for 8% of MOT failures. The reason is usually down to a suspension system becoming worn over the years and no longer working as it should. If you notice knocking or banging noises when driving your car over bumps or you experience lurching when driving, it’s a good sign there’s an issue with this important component.  

Why choose Wyatt’s for your MOT in Barnsley  

We hope that this article has helped to explain why vehicles can fail their MOTs. If you’re looking for reputable garages providing MOTs in Barnsley or Wombwell, look no further. We provide MOT testing at highly affordable prices, providing a trustworthy and honest service that you can rely on. Our skilled mechanics offer a while you wait service that’s quick and convenient. We can carry out any necessary repairs as quickly as possible too, ensuring your car is back on the road in no time at all. 

To book your car into your fully-equipped auto centre, call 01226 979 087. One of our friendly team is waiting to discuss your requirements with you. 



Wyatt Auto Services is a registered company in England.

Registered Number: 6341675

VAT Number: 916070443

© Wyatt Auto Services 2022. All Rights Reserved