One in three cars fails the MOT each year in the UK. That's a sobering figure, but here's the good news — a large proportion of those failures are for issues you could have spotted and often fixed yourself before the test.
Spending 30 minutes checking your car before the MOT can save you the hassle of a failure, the cost of a retest, and the inconvenience of being without wheels. Here's a systematic checklist covering everything MOT testers look for.
Before you start: check your past advisories
The smartest thing you can do before preparing for your MOT is check what came up last time. Previous advisories are issues the tester noted but that weren't serious enough to fail. A year later, those same items may have deteriorated enough to become failures.
Run a free MOT check to see your full MOT history, including every advisory and failure from previous tests. Our MOT readiness score highlights the items most likely to cause problems at your next test.
If last year's test flagged "brake disc worn but above limit" or "tyre approaching minimum tread depth," those are the things to look at first.
The complete pre-MOT checklist
1. Lights and signalling
This is the single biggest cause of MOT failures, and also the easiest to check.
Walk around the car and test every light:
- Headlights — dipped beam and main beam
- Front and rear indicators (both sides)
- Brake lights (all three if you have a high-level one)
- Rear fog light(s)
- Front fog lights (if fitted)
- Reversing light(s)
- Number plate light
- Hazard warning lights
DIY fix? Yes. Most bulbs cost under £5 and take minutes to replace. Check your owner's manual for the bulb type. If a bulb keeps blowing, there may be a wiring fault — that's one for a garage.
2. Tyres
Tyre failures are the second most common MOT issue.
Check:
- Tread depth — The legal minimum is 1.6mm across the central three-quarters of the tyre, around the full circumference. Use a tread depth gauge (under £3) or the 20p coin test: insert a 20p into the tread grooves. If you can see the outer band of the coin, the tread is likely below 1.6mm.
- Condition — Look for cuts, bulges, cracks, or exposed cord. Any of these is an automatic fail.
- Matching — Tyres on the same axle should be the same size and type. Mixing radials and cross-plies on the same axle is a fail.
- Pressure — Not specifically tested in the MOT, but incorrect pressure causes uneven wear that testers will notice.
DIY fix? You can check everything yourself, but tyre replacement needs a garage or mobile fitter. Don't leave it until the day before — tyre fitting slots can be booked up.
3. Windscreen and wipers
Check:
- Windscreen damage — A chip or crack larger than 10mm in the driver's swept area (Zone A, directly in front of the steering wheel) is a fail. Anywhere else in the swept area, the limit is 40mm.
- Wiper blades — Blades should clear the screen cleanly without streaking, smearing, or juddering. Perished rubber or bent arms will fail.
- Washer fluid — The washers must produce a jet of fluid that clears the screen effectively. Top up the washer bottle and check that the nozzles aren't blocked (a pin can clear them).
DIY fix? Wiper blades are a straightforward swap — buy the correct size for your car (the packaging or a reference guide at the shop will tell you). Windscreen chips can often be repaired for around £30–£60, which is far cheaper than replacement.
4. Mirrors
You need a minimum of two mirrors: the interior rear-view mirror plus the driver's side door mirror. If the interior mirror is missing, you need both door mirrors.
Check:
- Mirrors aren't cracked, broken, or missing
- They can be adjusted properly
- The glass isn't so deteriorated that visibility is affected
DIY fix? Replacement mirror glass clips into most modern cars without tools. Complete mirror units are more involved but manageable.
5. Seatbelts
Check every seatbelt in the car:
- Pulls out smoothly and retracts fully
- The buckle clicks in firmly and releases cleanly
- No fraying, cuts, or damage to the webbing
- The mounting points are secure
DIY fix? Seatbelt replacement is a safety-critical job best left to a professional. However, a seatbelt that won't retract can sometimes be fixed by cleaning the mechanism — pull it fully out and let it retract slowly several times.
6. Horn
Press it. It should produce a continuous, uniform sound loud enough to be heard by other road users. A weak, intermittent, or silent horn is a fail.
DIY fix? Sometimes a horn issue is just a blown fuse (check your fuse box). If the horn unit itself has failed, replacement is straightforward on most cars.
7. Brakes
This is harder to check thoroughly without equipment, but you can catch obvious problems.
Check:
- Brake pedal — Should feel firm, not spongy. It shouldn't sink to the floor when held.
- Handbrake — Should hold the car on a slope. If it clicks more than about 6–8 times, it may need adjustment.
- Pulling — If the car pulls to one side when braking, there's an imbalance.
- Noises — Grinding or squealing indicates worn pads or discs.
- Brake fluid — Check the reservoir level. If it's low, top it up — but low brake fluid often means worn pads, so investigate.
DIY fix? Brake pad replacement is within the ability of a competent DIYer, but if you're not confident, this is absolutely a job for a garage. Brakes are safety-critical — get them right.
8. Exhaust and emissions
Check:
- Exhaust condition — Look underneath for holes, excessive rust, or loose sections. A blowing exhaust is often audible as a rattling or hissing sound.
- Emissions warning light — If your engine management light is on, the car will almost certainly fail the emissions test. Get the fault codes read before the MOT.
- Smoke — Excessive blue or black smoke on startup or acceleration indicates a problem that will fail the emissions test.
DIY fix? Minor exhaust repairs (clamps, sealant) can be done at home, but most exhaust work needs a garage. An engine management light requires diagnostic equipment to identify the fault.
9. Number plates
Both plates must be present, securely fixed, clean, and legible. The characters must be correctly spaced and formatted — no creative fonts or illegal spacing.
DIY fix? Clean dirty plates. Replace damaged plates — you'll need your V5C or other proof of entitlement.
10. Bodywork and structure
Testers check for:
- Sharp edges — Rust holes or damaged panels that could injure pedestrians
- Excessive corrosion — Particularly to structural areas (chassis, subframe, suspension mounting points)
- Doors — Must open and close securely from inside and outside
- Boot/tailgate — Must latch securely
DIY fix? Minor surface rust can be treated with rust converter and touch-up paint. Structural corrosion is a serious issue that needs professional assessment.
Book your MOT at the right time
You can test your car up to one month before the current MOT expires without losing any days on the new certificate. This gives you a buffer — if the car fails, you have time to arrange repairs and a retest without driving around without a valid MOT.
You can compare garage prices online to find competitive MOT rates near you. The maximum fee is £54.85, but many garages charge £30–£40, and some offer free or discounted MOTs when combined with a service.
After the test
If your car passes with advisories, don't ignore them. Advisories are early warnings — a "tyre approaching minimum tread" advisory in April will likely be a failure by October.
If it fails, you have the right to a free partial retest if repairs are done at the same garage within 10 working days. Read our guide on what to do if your car fails its MOT for your options.
Check your MOT history now
Start your preparation by checking what testers found last time. Run a free MOT check to see your complete test history, including every advisory and failure. You can also see when your next MOT is due and check your car's tax status while you're at it.
For a deeper look at what each advisory actually means, see our guide to MOT advisories explained. And if you want to understand the most common failure points across all vehicles, check out the most common MOT failures.