There are some recent MOT test changes you need to be aware of coming into place during May 2018. The new MOT test is introducing two major changes to the way vehicles are categorised and how diesel cars are tested. Read on to ensure you’re aware of the way your vehicle is tested.

What are the MOT test changes?

Before going to have your MOT in Milton Keynes you do everything in your power to ensure your vehicle lasts because let’s face it, no one wants there pride and joy to fail its MOT. When you receive your pass or fail certificate, you will notice faults on your vehicles will be classified as Minor, Major and Dangerous.

Additionally, diesel vehicle will also notice a change in the way their cars are tested. Any diesel vehicle with a diesel particulate filter which emits any visible colour of smoke will receive a fail. The technician will also be able to establish whether the owner of the car has tampered with their diesel particulate filter, the car garage also has the right to refuse an MOT test where they feel the DPF has either been removed or rewelded in any way. There is only one exception for a car garage to test a DPF that has been changed if you can provide the mechanic with a legitimate reason and evidence it needed a filter cleaning.

What do the three new classifications mean?


Minor faults are those that the mechanic feels are more of an advisory however you need to be made aware of. If you have been given a minor fault on your pass certificate, this indicates that it isn’t a hazard but could become a potential issue in the future so should be kept an eye on.


A major fault is classified as a fault with the car which needs to be fixed straight away; this normally means you are unable to drive the car away from the garage until it has been fixed. If your car receives a major fault, it is classed as an instant fail. Before you can leave with the vehicle, the car will need to be repaired and then retested before the car can be classed as roadworthy.


A dangerous fault is an issue with the vehicle that would put yourself or other road users in immediate danger. Any dangerous faults will be classed as a matter of urgency; this indicates the car needs to be fixed straight away.

If you are caught driving your car with a major or dangerous fault, it is now classed as a criminal offence to do so; you could receive up to a £2,500 fine and up to three penalty points on your licence. Your vehicle is recorded straight away and put in the national database as being no longer roadworthy.

spanner enginer

How will MOT test changes affect you?

If you have a diesel vehicle, you don’t have to worry, just ensure you have checked to make sure your diesel particulate filter is intact. If you are going to purchase a second-hand diesel car we recommend you ensure this is fitted, has not been tampered with and if it has make sure you have the relevant paperwork which states why it needed changing.

Before going ahead with your MOT test, there are a few checks you should be doing at home. These include checking all light bulbs, windscreen wipers and tyres. These are the three main aspects of your car that can receive a simple fail.

Windscreen wipers should be checked for rubber missing, not only can they be ineffective, they can ruin the glass on your vehicle which will make your visibility worse. We recommend taking a look at for windscreen wipers. Tyres are easy to check at home, you should be looking out for the tyre tread this can be testing using a tyre gauge from Wiggle. Your tyre tread should never go below 1.6mm if it does your tyres will need replacing.

Common MOT test failures that can be avoided

There are a range of common MOT test failures that come up often here at Unit18 Automotive, so make sure you check your vehicle before bringing it in. There is nothing worse than your car failing for something you could have fixed or prevented.

Fuel Caps

Fuel caps are an aspect of your vehicle that gets check throughout your MOT test. If your fuel cap is loose, unsafe or no longer secure, you could fail your MOT test. Another fuel part to consider is if your car is full of petrol before taking it in. If your car is extremely low on petrol or diesel, you could be failed as the mechanic may be unable to carry out a range of tests.

man checking engine

Car lights and indicators

Have you ever seen someone driving around with only one headlight? A dimmed headlight or indicator can be deemed as an MOT test fail. Lights are something you can test easily at home, while the car is on ask someone to walk around a check all lights. Alternatively, you can drive your car close to a wall or fence to check the reflection of the lights.

Brake lights

Brake lights are one of the biggest MOT test failures here in the UK; we believe it is because they are one of the only lights you cannot physically see. If your brake lights are working intermittently, not at all or are constantly on it can be extremely dangerous for other road users. You should check every month if your brake lights are working as you can be pulled over by the authorities for dangerous driving. We recommend testing your brake lights the same way as your car lights either have someone walk around the back of the car while your lightly apply the brake or reverse up against a wall and you should see the brake light.


Before having your MOT test done, we recommend reading all about the recent MOT test changes on Ensure all maintenance is done on your vehicle before taking it for an MOT, to prevent your car from failing.

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