MOT Preparation Checklist: 15 Things to Check Before Your Test

Around a third of all MOT failures in the UK are caused by simple issues that any driver could spot and fix before the test. A blown bulb, low washer fluid, or a bald tyre can mean the difference between a pass and an expensive retest.

This checklist covers the most common failure points and takes about 30 minutes to work through. Fixing these items yourself could save you time, money, and the hassle of a failed test.

1. Lights: All Bulbs Working

Lighting faults are the single biggest cause of MOT failures, accounting for around 18% of all fails. Check every light on the car:

• Headlights — dipped and main beam on both sides
• Sidelights (parking lights) — front and rear
• Brake lights — ask someone to press the pedal while you check, including the high-level brake light
• Indicators — all four corners plus side repeaters (if fitted)
• Rear fog light(s) — at least one must work
• Reversing light(s) — at least one must work
• Number plate lights — often overlooked, easy to replace
• Hazard warning lights — all indicators must flash simultaneously

Replacement bulbs cost £2–£10 and take minutes to fit on most cars. Headlight bulbs on some newer models may require removing the bumper — in that case, get a garage to do it.

2. Tyres: Tread, Damage, and Pressure

Tyres are the second most common failure category. Check:

• Tread depth: Legal minimum is 1.6mm across the central three-quarters. Use a 20p coin — if you can see the outer band, the tyre is close to or below the limit
• Condition: Look for cuts, bulges, or cracks in the sidewalls. Any structural damage is an instant fail
• Matching: Tyres on the same axle must be the same size and type. Mixing radial and cross-ply on the same axle is illegal
• Pressure: While not an MOT failure on its own, correct pressure prevents uneven wear that is a failure item

3. Wipers and Washers

Windscreen wipers and washers are tested together. The wipers must clear the screen effectively without leaving large smears, and the washer jets must deliver fluid to the windscreen.

• Wiper blades: Replace if they judder, streak, or leave unwiped arcs. Replacement blades cost £10–£25 and are easy to fit
• Washer fluid: Top up the reservoir completely. Use screen wash additive — plain water can freeze in cold weather and may not clean effectively
• Washer jets: Make sure both jets spray onto the screen. If blocked, a pin can clear the nozzle

4. Windscreen Condition

The MOT tester checks the windscreen for damage that could impair the driver's view. The rules are specific:

• Zone A (a 290mm strip directly in front of the driver): A chip or crack larger than 10mm is a fail
• Rest of the swept area: Damage larger than 40mm is a fail

If you have a small chip, get it repaired before the MOT. Chip repairs cost £30–£60 and most are covered by your car insurance at no cost (no claims bonus unaffected).

5. Mirrors

Your car must have at least two functioning mirrors, including the driver's door mirror. Check that all mirrors are:

• Securely attached and not loose
• Not cracked or damaged to the point they distort the view
• Adjustable (electric mirrors must respond to controls)

6. Horn

The horn must produce a continuous, uniform sound loud enough to warn other road users. Give it a quick press — if it sounds weak, intermittent, or doesn't work at all, it will fail. Horn repairs are usually a simple relay or fuse fix costing under £20.

7. Seatbelts

Every seatbelt in the car is tested during the MOT. Check:

• Retraction: Each belt should pull out smoothly and retract fully when released
• Buckle: Must click in securely and release with a single press of the button
• Condition: No fraying, cuts, or damage to the webbing
• Locking: Give the belt a sharp tug — it should lock and prevent further extension

8. Exhaust and Emissions

The MOT includes an emissions test. Common failure causes include:

• Visible smoke: Excessive blue (oil burning), white (coolant leak), or black (running rich) smoke
• Diesel Particulate Filter (DPF): If your diesel has a DPF, it must be present and functioning. A missing or tampered DPF is an instant fail. DPF issues are one of the biggest MOT failure items on diesel cars
• Exhaust leaks: Listen for blowing sounds, especially at joints and the manifold
• Catalytic converter: Must be present and functioning. Visually check for damage underneath

When to Book Your MOT

You can get your MOT done up to one month minus a day before the expiry date without losing any days on your certificate. Book early to give yourself time to fix any issues.

Booking tip: MOT centres tend to be busiest at the end of the month and on Mondays. Booking mid-week at the start of the month often means shorter wait times and more flexibility if you need a retest.

Check your MOT due date for free at gov.uk/check-mot-status.

What to Do If You Fail

If your car fails the MOT, you have options:

If the failure is classed as "dangerous", you must not drive the car until the issue is fixed. The car will need to be towed or transported to a garage.

Final Thoughts

A 30-minute check before your MOT can save you time, money, and stress. The most common failures — bulbs, tyres, wipers, and washer fluid — are all cheap and easy fixes that any driver can handle.

Book your MOT early, work through this checklist, and fix what you can before you go. If something more serious comes up during the test, at least you've eliminated the simple stuff first.

This guide is for general informational purposes. MOT standards and testing criteria are set by the Driver and Vehicle Standards Agency (DVSA). Visit gov.uk/getting-an-mot for official information.