A Guide To MOT Testing

Stumped about what actually happens in an MOT test? Well, stop your crying and hair-pulling, because I’m here to help solve all your car maintenance nightmares .

Here’s a guide to MOT testing so that you find out what your car is going to be tested on.

What is an MOT test?

Short for Ministry Of Transport test, the MOT has been a legal requirement for any car over the age of three years, driving on UK roads, since 1960. It’s a yearly test that your car is put through to make sure that it’s safe, roadworthy and not polluting over permitted emissions guidelines – you have to get it carried out every annually if your car is over three years old.

How are you scored in an MOT?

In May 2018, the way that MOT's are scored changed and a number of new categories for defects were added. There are now officially four types of defects:

Dangerous defects

This is the most serious type of defect. These are essentially major defects that are also classed by the Government as a danger to you, your passengers and other road users. Think things like, no working brake lights, a windscreen that has a 10cm chip in it and flat tyres.

Getting one dangerous defect is an instant fail.

Major defects

A major defect is just as serious as a dangerous defect and it'll result in a MOT failure. Major defects are things like the washer bottle not being filled up, your oil leaking or your wipers being in a poor condition. Getting one major defect is a fail.

Minor defects

Minor defects are a problem that needs to be fixed as soon as possible, but they won't cause you to fail the MOT. They could become a more serious problem if not addressed.


These are small issues that could become problems if not addressed now or in the future. An advisory won't cause you to fail your MOT.

What is tested during an MOT?

The short answer is: quite a lot. The long answer is below! Here are the main things that are tested during an MOT and what the tester is looking for and marking your car on:

Vehicle Identification Number and number plate

The tester will make sure that the Vehicle Identification Number is clearly visible on your car (normally in the corner of the dashboard or on a front door), as well as making sure that your number plate meets the right regulations in terms of format, size, font and spacing.


You lights will be tested to check that they’re working correctly, are positioned properly and are the right colour.


The condition and operation of your steering will be checked to make sure it’s working as it should be.


The suspension of your car will be checked to confirm it’s working safely.

Wipers and washers

The condition and the sweep of the wipers will be tested to make sure that they work properly and give you a clear view of the road. Your washer bottle will also be checked to make sure it’s holding water and isn’t cracked.


The tester will do a visual check of your windscreen for deep scratches, chips and cracks. You’ll be allowed damage to the size of 10mm in the driver’s direct field of vision and 40mm of damage in a part of your windscreen outside of this.


Your horn will be blown to check that it’s loud enough and can be heard clearly. It’ll also be checked to make sure it’s appropriate for your car (that means you won’t be able to install an oil tanker-style foghorn, I’m afraid).

Seats and seatbelts

A really important part of your car in terms of safety, special attention will be given to the type of seatbelt that’s in your car, as well as their condition, operation and overall performance.

Fuel system

Without your fuel system, your car obviously isn’t going anywhere. That’s why it’s one of the key parts of your car tested during an MOT. You car will be checked for any leaks and the condition of the fuel cap to make sure that it’s sealing correctly.


We’re going to need to be investing in boats soon because of sea level rises, caused by the carbon emissions we’re creating, if we’re not careful. That’s why your car can automatically fail its MOT if it’s giving off emissions over the permitted amount. The tester will check that your car’s emissions fall within the correct guidelines and will also check that your exhaust is completely sealed and not too noisy.


The overall condition of your bodywork will be assessed in the MOT. Any sharp edge will be an instant fail and severe corrosion will be a fail too.


The doors will be opened and closed to check that the latches work correctly and that they can be opened from each side.  

Wheels and tyres

The wheels of your car will be checked for their tread depth, their size and condition.


The condition, performance and operation of the brakes will be tested to ensure that the braking system of the car is working properly.