How to Prepare Your Car for an MOT

First: Know When the Test Is Due

A car needs its first MOT three years after first registration in Great Britain (four years in Northern Ireland), then every year after that. You can test up to a month (minus a day) before the current certificate expires and keep the same renewal date. If you're not sure of your date, check it free — when is my car due an MOT explains exactly how.

The 15-Minute Pre-MOT Checklist

Lights and signals

Lighting defects are the single most common MOT failure category, and almost all are trivial to fix. With a helper (or a reflective garage door), check headlights on dip and main beam, sidelights, brake lights, reversing light, fog lights, indicators, hazards and the number-plate lamps. Replace any blown bulb and clean cloudy or dirty lenses.

Tyres and wheels

The legal minimum tread depth is 1.6mm across the central three-quarters of the tyre, all the way around. Use a tread gauge or the 20p test — if the outer band of a 20p coin is visible in the groove, the tyre is close to the limit. Also look for cuts, bulges, cracking and uneven wear (which can signal suspension or alignment problems), and check the tyres are inflated to the recommended pressures.

Driver's view of the road

Top up the washer fluid — an empty bottle is a genuine MOT defect — and replace wiper blades that smear or judder. Check the windscreen for chips and cracks: damage in the area swept by the wipers, particularly directly in the driver's line of sight, can fail the test depending on its size. Remove anything stuck to the glass that blocks the view, and make sure both required mirrors are intact and secure.

Inside the car

• Press the horn — it must work and be loud enough to hear.
• Pull every seatbelt sharply to check it locks, and inspect the webbing for cuts and fraying.
• Check seats are secure and the driver's seat adjusts properly.
• Turn the ignition on and watch the dashboard: an illuminated engine management light, or warning lamps for ABS, airbags or electronic stability control, are MOT defects. Get faults diagnosed before the test.

Outside the car

• Number plates must be clean, securely fitted, undamaged and in a legal font with correct spacing.
• Check for fluid leaks under the car after it's been parked overnight.
• Open and close the bonnet, boot and all doors — they must shut securely.
• Listen to the exhaust from cold: blowing or excessive smoke points to a problem worth fixing first.
• Give the car a quick clean. A tester can refuse to test a vehicle that's excessively dirty or full of clutter.

What You Can't Easily Check Yourself

Brakes, suspension and emissions are tested with equipment you won't have at home — and along with lights and tyres they make up the bulk of failures. You can still pick up clues: a car that pulls to one side under braking, grinds, knocks over bumps, or sits unevenly is telling you something. If you've noticed any of these, a garage inspection before the MOT is usually cheaper than a failure and retest. For the full list of what the tester examines, see what does an MOT check, and for a walkthrough of test day itself, what happens at an MOT.

If the Car Fails

A failure lists each defect as dangerous, major or minor. Dangerous and major defects mean a fail; a dangerous defect means the car must not be driven at all until repaired — even if the old certificate hasn't expired. If you leave the car at the test centre for repair, a partial retest within 10 working days is normally free; take it away and the retest rules vary, so ask the centre before you decide. The failure (and any advisories) will appear permanently on the car's public MOT history, which is exactly why used-car buyers should always read it — our guide to checking MOT history online shows what to look for.