The number one fail. Turn everything on and walk round: sidelights, dipped beam, main beam, front and rear indicators and hazards, brake lights (all three, including the high-level one), reversing light, rear fog, and the little number-plate lights. Cracked or badly discoloured lenses count too. Bulbs are pounds; a fail is a return trip.
Tread must be at least 1.6mm across the middle three-quarters of the tyre, all the way round. The quick test: put a 20p in the main grooves — if you can see the outer band, it's close to the limit. Look for cuts, bulges, cracking and cords showing. Check pressures. Below 1.6mm is a dangerous defect: the car can't leave the test centre on it.
Wipers must clear the screen without smearing or split blades. Washers must work and the bottle must have fluid in it — an empty bottle is a fail, which is about the cheapest fail there is. Chips: anything over 10mm in the area swept in front of the driver, or 40mm elsewhere in the swept area, fails. Take down the air freshener, dashcam and phone mount if they sit in the driver's view.
Press the horn. Pull each seatbelt fully out and let it retract; check the buckle clicks. Make sure the driver's seat locks. Start the car and watch the dash: engine management, ABS, airbag, power steering and electronic parking-brake lights must all go out — since 2018 any of them staying on is a major fail. Check the handbrake holds firmly.
Number plates clean, legible and the correct font and spacing. Mirrors present and not cracked. Doors, bonnet and boot open and close and latch. Fuel cap seals. Have a look underneath for anything hanging down or obviously leaking.
Brakes, suspension, steering play, exhaust condition and emissions all need a lift and the right kit. If the car's had a hard year or you've noticed a noise, a free brake check or a service before the MOT finds it on your terms.
Don't panic-fix. If you're not sure something's a fail, leave it and mention it at the desk. It's better to have a tester look than to pay for a repair that wasn't needed.
