What is checked in an MOT?
Roughly a quarter of the MOT failures we see are things the owner could have sorted on the drive in five minutes. Bulbs, wipers, screenwash, a chipped screen. Here’s the whole list, and the bit worth doing yourself first.
Five minutes on your own drive
- Every bulb. Dip, main beam, sidelights, indicators front and back, brake lights including the high-level one, reverse, fogs, number plate lights. Get someone to stand behind you for the brake lights.
- Tyres. Legal minimum is 1.6 mm across the central three quarters, all the way round. Look for cuts, bulges and one edge wearing faster than the other.
- Wipers and washers. Top the screenwash up — an empty bottle is a fail. Check the blades don’t smear or skip.
- Screen and mirrors. A chip bigger than 10 mm in the driver’s swept area fails. All three mirrors present and secure.
- Horn, belts and boot. Sound the horn, tug each seatbelt sharply so it locks, and empty the boot so the tester can reach the spare and jacking points.
- Warning lights. Airbag, ABS, engine management and brake warning lights on the dash are a fail on their own.
None of this is us being helpful for the sake of it — a car that fails on a £4 bulb costs you a second trip and costs us a bay.
What the tester works through
Outside the car
- Lights, indicators and reflectors
- Number plates and their condition
- Doors, latches, mirrors, wipers
- Bonnet and boot fastening
- Bodywork with sharp edges
- Towbar security, if fitted
Inside
- Seatbelts and their anchorages
- Seat security and driver’s seat adjustment
- Horn
- Warning lights on the dash
- View of the road and screen condition
- Speedometer and steering wheel
Underneath and on the rollers
- Brake performance and balance
- Brake pipes, hoses, discs and pads
- Suspension, shocks and springs
- Steering joints and play
- Structure and corrosion in prescribed areas
- Exhaust security, leaks and emissions
- Fuel system leaks
- Tyres and wheels
An MOT is not a service
This trips people up every year. The test is about roadworthiness and emissions on the day. It says nothing at all about:
- Engine condition, oil, or how long the cambelt has left
- Clutch and gearbox
- Air conditioning
- Battery health
- Coolant, brake fluid condition or filters
- Anything that’s about to fail but hasn’t yet
A car can pass its MOT on Monday and lose its clutch on Friday, and both are entirely normal. That’s what servicing is for.
Two that come up constantly
What’s the legal tread depth?
1.6 mm across the central three quarters and around the whole circumference, for cars and light vans up to 3,500 kg. We’d replace at 2.5–3 mm because wet braking falls off long before the legal limit — but that’s advice, not a rule.
Does the MOT check the engine?
Only its emissions and whether anything is leaking. Compression, oil condition, cambelt age — none of that is in the test.
Will a warning light fail it?
Airbag, ABS, brake and engine management warning lights are failures in their own right. Worth getting the light read before the test rather than after.
Is a cracked bumper a fail?
Only if it has a sharp edge or is insecure. Cosmetic damage on its own isn’t an MOT matter.