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  • Writer's pictureColwills Garage

What Can Cause You to Fail an MOT?

The Ministry of Transport (MOT) test is a common but vital part of owning a car. All vehicles that are more than three years old need to have an MOT once a year, which helps to keep everybody on the road safe, including yourself.

An MOT shouldn’t be something you anticipate with concern – after all, it’s a service that makes your car safer for yourself and others. However, we understand if you’re worried about potentially failing your MOT.

Did you know that the majority of MOT failures are due to relatively minor issues that can be resolved before your test? In this article, we look at some frequent reasons for cars failing an MOT, so you can take steps to help your vehicle pass before you reach the MOT garage.

How Does a Car Fail an MOT?

MOTs inspect your car and categorise any faults under these three terms:

  • Dangerous

  • Major

  • Minor

If your vehicle has any faults classed as dangerous or major, the garage will give you a VT30 form, which is a refusal to give your car an MOT in its current condition. Your vehicle can pass an MOT with minor faults, but these will still need to be fixed.

The Most Common Reasons for Failing Your MOT

The most recent figures from the UK Government suggest an MOT fail rate for Classes 3 & 4 – cars, vans and small passenger vehicles – of just under one-third. Out of all failures, here are the most common reasons, ranked for the percentage of failures attributed:

  1. Lights & Signals

  2. Suspension

  3. Brakes

  4. Tyres

  5. Driver’s View

Lights and Signals

By far and away, the most common cause of MOT failure is lights. A blown bulb is all that’s needed, and it’s something easily avoided.

Before sending your car for an MOT, perform a manual check to make sure all your lights are working and effective. Make sure to check your indicators and number plate lights, also.

For some cars, the plastic light cover can get misty, which reduces the light’s effectiveness. Cleaning your lights will help avoid this from causing an MOT failure.


The suspension is the second most common cause of MOT failure. The reason here is often potholes, which can cause damage to your car’s systems.

Checking your suspension before an MOT sounds daunting, but there are a few simple things you can do.

First of all, check that the car doesn’t make any unnatural clunking sounds when driving, cornering or over bumps. When at a standstill, check the vehicle sits level, and there’s no abnormal dip towards one corner.

You can also press down on each corner of your car to check it returns to its normal position and doesn’t bounce around too much.


Brakes are easy to check but still result in over one-in-ten MOT failures.

Make sure that your car can stop at a safe distance and pay attention to any squealing noises which may indicate worn brake pads. You need to test your handbrake also, which is best done on an incline.


It’s impossible to overstate the importance of having adequate tyres – after all, that’s your connection to the road.

The most common issue with tyres and MOTs is the tread. Check your tyres still have 1.6mm of tread across their centre three-quarters, or you could be hit with a failure and also a hefty fine. Also check the tyres for any lumps, cuts or uneven wear, and also that you have the right size for your vehicle.

Driver’s View

Making sure you can see the road without any distractions is driving 101, yet people still fail MOTs as a result. Take a minute to check that there are no issues that could prove costly in your MOT test.

Make sure that there are no sat-navs or hanging ornaments (like air fresheners) that could be deemed to be blocking your view. Make sure there are no significant chips or cracks on the windscreen and consider getting them repaired before your MOT.

You should also consider some externals, such as your windscreen wipers and bonnet (is it secure?). Another uncommon but potential fault is if you have no screenwash, so make sure you’re topped up!

By taking five minutes to inspect your car for yourself, you can drastically reduce the likelihood of failing your MOT for something avoidable. It is also a good habit to perform these checks yourself monthly, at least, as it all contributes to making the roads a safer place for everyone.

Here at Colwills Garage, we can undertake Class 4 & 7 MOTs, covering all cars and light commercial vehicles up to 3,500kg. If you need to renew your MOT or simply want a service, why not get in touch with our team today?

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