The MOT Test Explained – What Does an MOT Check For?

What is an MOT?

An MOT is a legally-required annual service check, whereby your vehicle is checked over by a mechanic to ascertain how roadworthy it is. An MOT service provider will have a series of criteria to measure your car’s performance against, failure of which can range in classification from a minor or major to a dangerous defect – with ‘advisories’ given for anything that has not yet failed, but may do without adequate service and repair before the next MOT. In order for your car to continue to be road-legal, it must pass its MOT.

An MOT is failed if any one major or dangerous defect is discovered. A car can still be driven with a major defect if still covered by the previous year’s MOT, otherwise it can only be driven to a pre-arranged service or repair appointment. However, a dangerous defect means your car cannot be driven under any circumstances whatsoever, and the defect must be repaired before it can be driven. Either way, after your car’s repair you must book a re-test to determine if your car is now roadworthy.


What is Checked Over in an MOT?


Before you book your MOT online, it can be helpful to know exactly what your MOT test will check for:

Lights, Reflectors and Electrical Equipment
MOT testers will check your headlamps, brake lights and indicators , as well as electrical equipment which controls these and other functions. If you have a defective light, whether the bulb simply needs replacing or there’s an electrical fault, this can represent a fail. Any abrasion, rusting or cracking that obstructs the passage of light could also cause a fail.

Body, Structure and General Items

Your bodywork may have been impacted at some point since the last MOT, resulting in sharp edges or damage which could cause risk of injury. While looking for this, testers will also examine your car’s framework and towbar for any signs of rust, corrosion or damage.

Testers will check your braking systems work as intended, from levers and pedals to the pads themselves. If there is any evidence of brake fluid leakage, or your brake pads are towards the end of their life, these could constitute failure.



Seatbelts are a deeply important safety feature, and their correct operation must be ascertained by your tester in order to pass. Any evidence of particularly bad seatbelt wear or damage can cause a fail.

Your tyres must be above the legal minimum requirement for tread depth – if any of your tyres’ central treads measure less than 1.2mm depth, you will fail your MOT and be required to replace them before you can drive your car.


Exhaust Emissions


If your exhaust exhibits a major leak, or is producing unsafe emissions, your vehicle will not pass its MOT; these issues are often due to issues with the catalytic converter, or major corrosion of the exhaust pipe. Minor leaks or corrosion tend not to cause failure, instead being noted as minor defects or advisories.

Mirrors and Windscreen

An MOT also tests the visibility in your windshield and rear-view mirrors, otherwise known as ‘indirect vision devices’; loose or slightly damaged indirect vision devices garner a minor defect, while any inadequate, excessively damaged or missing mirrors warrant a major defect. Any cracks in your windshield will also warrant a defect – though a failure will only be caused by a crack larger than 40mm.

Steering and Suspension

Tests surrounding steering and suspension are particularly in-depth, with the number of moving parts and systems at play. Testers will examine the condition of any steering gear, as well as whether any power steering fluid leakages are present. Any looseness, excessive motion or tendency to breakage could land you a fail. Any issues with any element of your suspension or axles will also result in failure.