MOT preparation checklist: what to check before your MOT

Lights

• Headlights (dipped and full beam)

  Walk to the front with the engine running and check both headlights illuminate. A blown bulb costs £5 to £30 to fix yourself and causes an immediate MOT failure.

• Rear lights and brake lights

  Ask someone to stand behind the car while you press the brake pedal, then check reversing lights by engaging reverse. Replace any failed bulbs before the test.

• Indicators (all four corners) and hazard lights

  All four indicators must flash at a consistent rate. A very fast flash usually means a bulb has gone.

• Number plate light

  The rear number plate must be illuminated at night. This small bulb is a common and easily overlooked failure point.

• Fog lights (if fitted)

  Front and rear fog lights must work if the car is fitted with them. Check the switch and confirm the dashboard indicator comes on.

Tyres

• Tread depth: minimum 1.6 mm across the central three-quarters

  Use a 20p coin: if the outer band is visible when inserted into the tread groove, the tyre is likely below the legal limit. The minimum is 1.6 mm; most testers flag under 2 mm as an advisory.

• Tyre condition: no cuts, bulges or exposed cord

  Run your hand around the sidewalls and look for bulges, cuts or any exposed fabric. Any of these is an automatic failure.

• Tyre pressure

  Under-inflated tyres can cause handling issues flagged at the test. Check the pressures against the sticker inside the driver's door frame and inflate to the correct level.

• Spare tyre (if a full-size spare is fitted as standard)

  Some cars have the spare as part of the MOT check. Check your handbook. Space-savers are generally not tested but should be in serviceable condition.

Windscreen and visibility

• Windscreen: no chips or cracks in the driver's direct line of sight

  A chip larger than 10 mm anywhere in a 290 mm central band, or 40 mm elsewhere in the swept area, causes a fail. Small chips can be repaired for £20 to £60 rather than a full replacement.

• Wipers: clear, streak-free, no torn blades

  Turn on your wipers and washer. If they smear or leave a wide arc uncleared, replace the blades. A pair of standard wiper blades costs £15 to £40.

• Washer fluid reservoir: not empty

  An empty washer bottle means the washer jets cannot demonstrate function during the test. Top it up before you go.

• Mirrors: both door mirrors and interior mirror present and not cracked

  All mirrors required by the car's original specification must be present and give a clear rearward view.

Brakes

• Brake pedal feel: firm, not spongy or sinking

  A spongy pedal can indicate air in the brake fluid or a failing master cylinder. This is a safety item and a tester will identify it immediately on the brake test.

• Handbrake: holds the car on a slope

  Park on a hill and release the footbrake. If the car rolls with the handbrake fully applied, the cables or rear brakes need adjustment.

• Brake warning light (not illuminated)

  A brake warning light that stays on during normal driving is a fail. Check the fluid level first: low fluid often triggers it and can indicate worn pads.

Bodywork and structure

• No sharp edges or corrosion that could injure a person

  Rust that has eaten through panels and left sharp edges is assessed as a danger to pedestrians. Surface rust does not fail unless it has structurally compromised a load-bearing section.

• Doors open, close and latch properly

  All doors must open from inside and outside. A door that will not close securely is an immediate fail.

• Boot or tailgate: closes and latches

  The boot lid must be able to be secured so it cannot open unexpectedly while driving.

Interior and mechanical

• Horn: works

  Press and release the horn. If there is no sound, check the fuse before booking the test.

• Seatbelts: all present, click in, retract and hold under tension

  Check every seatbelt in the car, not just the front two. Pull the belt sharply: it should lock. Check the webbing for fraying or cuts.

• Dashboard warning lights: all off after engine has warmed up

  Engine management light, ABS light, airbag light and power steering warning light all on at the start of the MOT test will cause a fail. If any stay on, get them diagnosed with an OBD reader before the test.

• Fuel: enough for the test drive

  The tester needs to take the car on a short road test. Running out of fuel will at minimum cause delay; some garages charge an aborted-test fee.

Emissions

• Diesel: no visible black smoke at startup or under load

  Diesel particulate filter (DPF) problems are a common MOT fail on diesel cars. If the DPF warning light has been on, get the filter checked or forced-regenerated before the test.

• Petrol: catalytic converter not rattling

  A rattle from under the car is often a broken catalytic converter substrate. This affects the emissions test and will cause a fail.

Frequently asked questions

How long does an MOT take?

A standard MOT takes between 45 minutes and 1 hour. If the tester finds advisory items they want to discuss, or if a visual check requires further investigation, it can take longer. Plan for up to 90 minutes to be safe.

What are the most common reasons cars fail their MOT?

According to DVSA data, the five most common MOT fail categories are: lighting and signalling (defective bulbs, incorrect aim), suspension (worn components), brakes (worn pads, seized calipers), tyres (illegal tread depth or damage), and driver's view of the road (wiper blades, windscreen chips). All of these can be identified with the 15-minute pre-test check above.

Can I drive my car to the MOT test if it has a warning light on?

You can drive to a pre-booked MOT appointment even with a warning light on, provided the car is not dangerous to drive (for example, a brake system warning with no pedal feel would be unsafe). However, most dashboard warning lights will cause an automatic fail, so it is worth diagnosing the issue first.

What is a minor, major or dangerous defect in an MOT?

Since the 2018 MOT rule changes, defects are classified as: Advisory (note only, no fail), Minor (recorded but does not fail the test), Major (fails the MOT, car can still be driven away), or Dangerous (fails the MOT, car must not be driven until repaired). A car with a Dangerous defect cannot legally be driven from the test centre.

Does a service before an MOT help?

A full service addresses many of the mechanical items checked in an MOT: brake fluid condition, tyre tread, bulbs, oil and filter. Having a recent service does not guarantee a pass but reduces the chance of being caught out by wear items that have degraded since the last test.

How early can I book my MOT before it expires?

You can book and take your MOT up to one calendar month minus one day before it expires, and still retain the original expiry anniversary for the following year. If your MOT expires on 15 July, you can take the test as early as 16 June without losing any of the year's cover.

What happens if I fail my MOT?

If your car fails, the garage issues a VT30 failure document listing every fail item and advisory. You cannot legally drive the car on a public road (except directly to a pre-booked repair appointment) until the fail items are fixed and a pass certificate is issued. Many garages offer a free retest within 10 working days if repairs are done with them.