What Is Checked on an MOT? The Complete 2026 List

The MOT is a test of roadworthiness at a single moment in time. It is not a service, not a mechanical inspection, and emphatically not a guarantee that your car will still be sound next week. Understanding exactly what falls inside its scope — and what falls outside — is the difference between walking into a test with realistic expectations and being blindsided by a failure.

This guide covers every inspection area in the current DVSA testing standard for class 4 vehicles, which is what most cars, taxis and vans up to 3,000kg fall under.

What an MOT is, and what it is not

An MOT confirms that a vehicle met the minimum legal safety and environmental standards on the day it was tested. That distinction matters more than most people realise. A pass certificate issued in the morning has no bearing on a tyre that goes bald three months later, and it never implied the car was in good mechanical health to begin with.

The test is also strictly visual and functional. A tester inspects what can be seen, measured or operated without dismantling anything. They will not remove a wheel, drop the gearbox oil, or take off an undertray that is fixed in place. Where a component cannot be inspected because access is blocked, that itself can be recorded as a reason for rejection.

Three things people consistently, and reasonably, expect the MOT to cover, which it does not:

• The engine's mechanical condition. Compression, cambelt age, oil quality, turbo health — none of it is assessed.
• The clutch and gearbox. A slipping clutch or a gearbox that jumps out of third will pass an MOT without comment.
• General wear that is not yet a safety issue. Sagging suspension that still functions, air conditioning that has stopped working, a noisy wheel bearing that has no measurable play.

If you want that level of assurance, you need a service or a pre-purchase inspection. They answer different questions.

Lights and signalling

The single most common failure area, and the cheapest to avoid. The tester checks:

• Headlamps for operation, security, condition and aim. Misaligned beams are a very common failure and often result from a bulb being replaced incorrectly or a minor front-end knock.
• Sidelights, rear position lamps, brake lights including the high-level lamp where fitted, and the registration plate lamp.
• Indicators, including their flash rate, and hazard warning lights.
• Rear fog lamp — a single working rear fog lamp is required on vehicles first used from April 1980.
• Reversing lamps where fitted, and daytime running lamps on vehicles first used from March 2018.
• Headlamp levelling devices and cleaning systems where they form part of the original specification.

Colour, symmetry and security all count. A brake light that works but is held on with tape is still a defect, and a pair of headlamps where one has faded to a different colour temperature can be marked down.

Brakes

The tester examines the condition and operation of the entire braking system, then measures its performance on a roller brake tester or with a decelerometer.

Inspected items include brake pads and discs where visible, drums, hoses and rigid pipes, the master cylinder, servo, callipers, the parking brake mechanism, and the brake fluid level. Anti-lock braking and electronic stability control warning lamps are checked, and an illuminated ABS lamp is a major defect.

The performance test measures two things: total braking efficiency and the balance between the two sides of each axle. A car can have visually perfect brakes and still fail because one side is doing noticeably more work than the other, which is typically a sticking calliper or a contaminated pad.

Minimum efficiency for most cars is 50% for the service brake and 16% for the parking brake, though the exact figures vary with the vehicle's design and date of first use.

Steering and suspension

The tester checks the steering wheel and column, the rack, track rod ends, ball joints, wheel bearings, springs, shock absorbers and suspension arms and their bushes. Power steering is checked for operation, fluid level and leaks, and the electronic power steering warning lamp must not be illuminated.

Most defects here are found by levering components to detect play, so the grading depends heavily on how much movement there is. "Slight play" is typically an advisory; movement beyond a defined threshold becomes a major defect. This is why the same worn ball joint can be advised one year and fail the next without anything dramatic having happened.

Broken or corroded springs are a common and often unexpected failure, particularly on cars that spend winters on salted roads.

Tyres and wheels

Tread depth must be at least 1.6mm across the central three-quarters of the tyre, around its entire circumference. That definition catches a lot of people out: a tyre with plenty of tread in the middle but worn to the cords on one edge will fail, and edge wear usually points to an alignment or suspension problem worth investigating anyway.

Also checked:

• Tyre condition — cuts, lumps, bulges, exposed cords or ply, and perishing sidewalls.
• Correct tyre sizes and speed ratings for the vehicle, and matching types across an axle.
• Wheel security and condition, including damaged or badly buckled rims.
• Tyre pressure monitoring system warning lamp on vehicles first used from January 2012.
• Valve condition and security.

Spare tyres are not tested. Neither is the condition of a space-saver.

Seatbelts, seats and restraints

Every belt fitted to the vehicle is checked for condition, security and operation, including the retractor mechanism and, on inertia-reel belts, the locking action. Fraying, cuts and a belt that does not retract cleanly are all defects.

The airbag warning lamp is checked, and airbags fitted as original equipment must be present. Removing an airbag rather than repairing it is a failure.

Seats must be secure. The driver's seat must adjust and lock, and seat backs must be capable of being locked upright.

Body, structure and general condition

The tester inspects the vehicle's structure for corrosion, distortion and cracking, with particular attention to areas within 30cm of critical mounting points — seatbelt anchorages, suspension mounts, steering components and brake mountings. Corrosion in these "prescribed areas" is a failure, and the repair must be a proper welded one.

Also assessed: sharp edges or projections caused by damage or corrosion, the security of doors, bonnet and boot, and the condition of the towbar where one is fitted.

Exhaust, emissions and fuel system

The exhaust system must be secure, complete, without serious leaks, and must effectively silence the vehicle. The catalytic converter must be present if the vehicle was originally fitted with one.

Emissions limits depend on the engine type, fuel and date of first use. Petrol cars are tested for carbon monoxide, hydrocarbons and lambda. Diesel cars are tested for smoke opacity.

Diesel vehicles with a diesel particulate filter fitted from the factory face two additional rules that have caught out a great many owners since 2018:

• Any visible smoke of any colour from the exhaust is a major defect.
• Evidence that the DPF has been removed, tampered with or hollowed out is an automatic failure, and the tester must refuse the test if there are obvious signs of removal.

The fuel system is checked for leaks and the security of the filler cap, which must seal correctly.

The driver's view of the road

Windscreen damage is assessed by zone. In the area swept by the wipers directly in front of the driver — a 290mm-wide strip known as zone A — damage larger than 10mm is a failure. Elsewhere in the swept area, the limit is 40mm.

Wipers must clear the screen effectively, and washers must deliver enough fluid to do so. A torn wiper blade or an empty washer bottle is an easy, avoidable failure.

Mirrors are checked for presence, condition and security. Obstructions on the windscreen, including large satnav mounts, air fresheners and stickers, can be a defect if they sit in the swept area and impede the view.

Registration plates, VIN and other checks

Plates must be present, secure, correctly spaced and legible, with the correct font and no altered character spacing. A "personalised" plate with rearranged spacing is a straightforward failure.

The vehicle identification number must be present, legible and a single number. Additionally the tester checks the horn, the speedometer's presence and illumination, and the electrical wiring and battery for condition and security.

How defects are graded

Since May 2018 the test has used a four-tier grading system, and the wording matters:

The critical practical point: a minor defect is still a pass. Minor and advisory items both appear on the certificate and both go onto your vehicle's permanent public MOT record, which is why a car's history can show a long list of recorded items alongside an unbroken run of passes.

You can read the full history of any UK vehicle, including every advisory ever recorded against it, on any registration's MOT record. It is the single most useful free document available on a used car.

What happens if your car fails

If your vehicle fails with only major or minor defects and your existing MOT certificate is still valid, you may continue to drive it — the previous certificate remains in force until its expiry date. That surprises people, but a failure does not retroactively cancel a valid certificate.

If it fails with a dangerous defect, you must not drive it away under any circumstances. Doing so risks prosecution, and your insurance is very unlikely to respond to a claim.

If your previous certificate has already expired and the vehicle has failed, you can only drive it to a pre-arranged repair appointment or to a pre-booked MOT test.

Retests and when they are free

The rules on retest fees are more generous than most drivers assume:

• Leave the vehicle at the test centre for repair and the retest is free.
• Take the vehicle away and return it before the end of the next working day, and the retest is free for a specified list of straightforward items.
• Return within 10 working days for a partial retest covering only the failed items, and a reduced fee may apply.
• Return after 10 working days and you pay for a complete new test.

The specified-items list for a next-working-day free retest covers many of the cheap fixes: lamps, wipers, mirrors, registration plates, seatbelt condition, fuel filler caps, horn and several others.

The most avoidable failures

A meaningful share of MOT failures come down to items an owner could check in ten minutes in a driveway:

1. Blown bulbs. Walk round the car with the lights on and have someone press the brake pedal.
2. Washer fluid. Top it up. An empty bottle is a fail.
3. Wiper blades. If they smear or judder, replace them.
4. Tyre tread and pressures. Check across the full width, not just the middle.
5. Number plate condition. Faded, cracked or incorrectly spaced plates all fail.
6. Warning lamps. Turn the ignition to position two and check that the airbag, ABS and engine management lamps illuminate and then go out.
7. Horn. Press it.

None of these require tools, and together they account for a large slice of first-time failures.

Check what your car has failed on before

The most reliable predictor of what a car will struggle with this year is what it struggled with last year. Advisories in particular are a tester telling you, in writing, what is going to become a failure soon.

Every MOT test recorded in Great Britain since 2005 is public, including every advisory and every recorded mileage. Looking at your own car's record before booking tells you what to pre-empt; looking at a car's record before buying tells you what the seller may not.

If you are not sure when your test is due, you can check your MOT due date from the registration alone. If a previous certificate listed a defect you did not understand, the MOT defect library explains the common ones in plain English, including what they cost to fix.