MOT preparation checklist: the 12 things that fail most and how to check them at home

Roughly one in three cars fails its first MOT attempt, and the DVSA’s own figures say the same handful of items account for most of it: lights, suspension, brakes, tyres and “driver’s view of the road”. Most of those are visible from the driveway with a torch and ten minutes. This checklist covers the twelve items you can check yourself, what the tester is looking for, and what you can fix with parts from the boot rather than a garage bill.

1. Every bulb, including the ones you never see

Sidelights, dipped and main beam, indicators front, rear and side, brake lights (all three), reversing light, fog light and the number-plate lights. Number-plate bulbs are the single most common lighting fail because nobody checks them. Get someone to stand behind the car while you work through the switches, or reverse up to a garage door at dusk and watch the reflections. Replacement bulbs are a few pounds; note the type printed on the old bulb (H7, 501, P21W and so on) before ordering from our car bulbs range.

2. Tyre tread and condition

The legal minimum is 1.6 mm across the central three-quarters of the tread, around the whole circumference. The 20p test works — if the outer band of the coin shows, you are close — but a tread-depth gauge from our tyre and wheel tools is more honest. Look also for cuts, bulges and cords showing on the sidewall, and check the pressures against the sticker in the door shut.

3. Wipers and washers

The tester will run the wipers and washers. Smearing, split rubber or a blade that judders is a fail under “driver’s view of the road”. Blades are sized by length and fitting type; match both to your old blades. Top up the washer bottle with proper screenwash, not water, and check both jets aim at the glass.

4. Windscreen chips

A chip larger than 10 mm in the area swept by the driver’s wiper (the “A zone”), or larger than 40 mm elsewhere in the swept area, fails. Anything smaller is an advisory. Insurers usually repair chips free of excess, so get it done before the test rather than after.

5. Brakes: feel, noise, handbrake

You cannot measure brake efficiency at home, but you can notice a spongy pedal, pulling to one side, grinding or squealing, and a handbrake that needs more than a few clicks or will not hold on a hill. Pads and discs are in brake parts; if you are not confident, a garage brake check is cheap compared with a retest.

6. Horn

Press it. It has to work and it has to sound like a horn, not a novelty tune.

7. Mirrors

Both door mirrors and the interior mirror must be present, secure and not cracked in a way that obscures the view. A cracked glass is usually a stick-on replacement rather than a whole unit.

8. Number plates

Correct font, correct spacing, no cracks, not faded, both lit at night. Show plates, tinted covers and stuck-on screws that alter a character are automatic fails.

9. Seatbelts

Pull each belt fully out and inspect for fraying and cuts; check every buckle latches and releases; give each belt a sharp tug to confirm the inertia lock works. Belts in the back count too.

10. Dashboard warning lights

Engine management, ABS, airbag, power steering and tyre-pressure warnings are all fails if they stay on. A basic OBD2 reader from our diagnostic tools tells you why the engine light is on; sometimes it is a loose fuel cap or a sensor you can replace yourself.

11. Fluid leaks and exhaust

Look under the car after it has stood overnight. A drip of water from the air conditioning is fine; oil, coolant or brake fluid is not. Start the engine and listen at the exhaust for blowing and look for smoke. Excessive smoke or an exhaust that has come away from its mounts will fail.

12. Registration and the obvious

Bring the V5C if the tester needs it. Clear the boot so the spare-wheel well can be inspected, make sure the bonnet release works and that there is enough fuel to run the emissions test. Doors, boot and bonnet must open and close from the correct side.

What to keep in the car all year

A spare bulb kit, a tread-depth gauge, a tyre inflator, a set of wiper blades and a bottle of screenwash cover most of the items above. Put a reminder in your calendar a month before the MOT is due, work through this list on a Sunday morning, and the test becomes a formality.

Frequently asked questions

How early can I get an MOT without losing days?

Up to one month minus a day before the current certificate expires; the new certificate keeps the original expiry date, so you lose nothing.

What are the most common MOT failures in the UK?

Lighting and signalling, suspension, brakes, tyres and the driver’s view of the road (wipers, washers, windscreen). Lighting alone accounts for close to a third of failures.

Can I drive with a failed MOT?

Only to a pre-booked MOT test or to a garage for repairs, and only if the car has no dangerous defects. Driving otherwise is illegal and invalidates insurance.

Do dashboard warning lights fail an MOT?

Yes. Engine management, ABS, airbag, electronic power steering and tyre-pressure warning lights that stay on are failures.

Is a number-plate bulb really a fail?

Yes. Both number-plate lights must work; it is one of the most common lighting failures because it is rarely checked.