What does an MOT check?
An MOT checks that a car meets the minimum legal standards for safety and emissions on the day of the test. It is not a service and it does not look at the engine, clutch or gearbox, which is why a car can pass and still need work.
Updated 14 October 2026
The main areas the tester inspects
Brakes: their condition, how well they stop the car, and the handbrake or parking brake. Tyres and wheels: tread depth (at least 1.6mm across the central three-quarters of the tread, all the way round), cuts, bulges and that the tyres are the right type and size.
Lights: headlamps, sidelights, indicators, brake lights, fog lights, number plate lamps and the headlamp aim. Steering and suspension: wear, play and leaks. Seatbelts: every belt, its mounting and that it locks.
Visibility: the windscreen for chips and cracks in the driver’s view, the wipers and washers, and the mirrors. The body and structure: excessive corrosion or sharp edges, particularly near suspension and brake mountings.
Exhaust and emissions: leaks, noise, and the gases the engine produces against the limit for its age and fuel. Diesels with a diesel particulate filter fail if it has been removed or visibly tampered with.
Also on the list: the horn, the fuel system for leaks, the number plates (correct font, spacing and condition), the vehicle identification number, the registration matching the V5C, and dashboard warning lights such as the airbag and ABS lamps.
What an MOT does not check
The condition of the engine, clutch and gearbox. Oil level and quality. Cambelt condition. The bodywork beyond structural corrosion. Whether a past accident repair was done well.
That is the most important thing to understand about an MOT certificate when buying a car: it says the car met the minimum standard on one day. It says nothing about how the car has been looked after, which is what the service history and the MOT advisories are for.
How results are graded
Every fault found is recorded as dangerous, major or minor, and the tester can also add advisories. A dangerous or major fault is a fail. Minor faults and advisories are a pass, but they are written on the certificate and on the public record.
Advisories are the most useful part of an MOT history for a buyer or owner. An advisory for a corroded brake pipe this year is very often the fail next year.
Keeping track of it all
Odomint shows the full MOT history for any UK registration (every pass, fail, defect and advisory) and reminds you before your next test is due, so nothing on that list arrives as a surprise.
Common questions
Does an MOT check the engine?
No. The MOT does not assess the engine, clutch or gearbox. It checks emissions, and leaks, but not the mechanical condition of the engine itself.
What is the minimum tyre tread for an MOT?
At least 1.6mm across the central three-quarters of the tread, around the whole circumference of the tyre.
Will a warning light fail an MOT?
Some will. Warning lights for the airbag, ABS, electronic stability control, brake fluid and engine management (on newer cars) are part of the test.
Check any car before you buy it
MOT history, every advisory and the full mileage record are free for any UK registration. An Odomint Check adds outstanding finance, insurance write-offs, stolen markers and salvage history, with a £10,000 data guarantee.