Preparing for your MOT test can be stressful, especially if you are unsure what needs to be checked. But the truth is, a little planning goes a long way. Before heading to the garage, it helps to run through a few simple steps at home to avoid surprises. In this guide, we'll go over 24 things that will fail an MOT test, from lights to tyres and everything in between. We'll also explain why it’s just as important to check car insurance and make sure your paperwork is up to date. Think this your go-to car MOT checklist—clear, concise, and designed for real UK drivers like you.
1. Tyres
When you prepare for MOT, make sure your tyres are safe and legal. Ensure that they are not flat, worn out, or damaged. The tread depth should be at least 1.6mm; use the 20p test to confirm. Look for cracks, bulges, or stones stuck in the grooves. If anything looks wrong, have it checked or replaced. Faulty tyres are one of the leading causes of MOT failures; therefore, do not neglect this step.
2. Horn
Your horn isn't just there for fun; it's also an important safety feature. It should be loud enough for other drivers to hear and work with a single press. If it is weak, silent, or makes a strange sound, it may cause you to fail your MOT. The tester will check the horn to make sure it works properly. Give it a short blast before your test to make sure it's working properly.
3. Wipers
Wipers help keep your view clear, especially when it rains. If they leave streaks or make scraping noises, they might need replacement. Make sure that the wiper blades are not split or damaged. Don't forget to check your screen wash since an empty washer bottle is a surefire way to fail. Clear visibility is an important part of the MOT check, so keep your wipers in good condition.
4. Seatbelts
Seatbelts keep you safe, so they must be in good condition for your MOT (they are what can fail an MOT). Give each one a quick pull—if it locks in place, that's a good sign. Check for fraying, cuts, or anything else that could prevent it from working properly. If your seatbelts do not click in securely or look damaged, have them repaired before the test.
5. Number Plates
Your number plate should be clean, easy to read, and firmly attached. Remove any dirt or grime, especially if you have been driving over muddy roads. The letters and numbers must be the right size and spacing, or your car might fail the MOT. A damaged or loose plate is also a problem; repair or replace it if necessary before your MOT check.
6. Battery
If your battery isn't charged, your car might not even start, let alone pass a MOT. Check that the battery is securely fitted and the cables are not loose or rusted. If your car struggles to start or you've recently experienced battery problems, it's worth having it tested. A healthy battery makes sure that everything goes smoothly during the MOT.
7. Bodywork
Take a walk around your car and inspect the body panels. Dents, sharp edges, and loose parts can be problematic, especially if they pose a risk to pedestrians. Rust in key areas such as the brakes or suspension can also cause you to fail your MOT test. Fix any major damage before the test—it's not just about appearance; it's also about safety.
8. Brake Fluid
Brake fluid allows your car to stop safely. If it's too low or dirty, your brakes may not work properly. You can check the brake fluid level in the clear container under the bonnet; there should be a mark showing the minimum level. If it falls below that, top it up or have it checked. Good brake fluid is essential for passing your MOT and staying safe on the road.
9. Brake Lights
Brake lights warn traffic behind you that you are slowing down. To check them, hit the brakes and have someone check to see whether both lights turn on—or back up against a wall and watch for the reflection. If one of the bulbs is out or flickers, replace it before your MOT. Working brake lights are an easy way to improve your driving safety and pass your test.
10. Brakes
Brakes are one of the most important safety parts on your car. If you hear squeaking or grinding or your car pulls to one side while braking, have them checked. Worn-out pads or damaged discs can cause an MOT failure. Don't wait for a problem to arise; have it addressed as soon as possible to make sure that your MOT test goes smoothly and your car stops safely.
11. Check Your Tyres
Even if they look fine, give your tyres a proper once-over. Check the tread depth with a 20p coin and look for damage, such as bulges or cuts. The tyres should also be at the right pressure, which your handbook will specify. This step is easy to overlook but extremely critical. Poor tyre condition is a common cause of MOT failure.
12. Doors
All car doors should open and close properly from both inside and out. This includes both the boot and the bonnet. If a door does not latch, is jammed, or doesn’t unlock, that’s a failure. Check to make sure that they are not stuck and that the handles are working properly. It’s a small check but it's necessary to keep your car roadworthy—and safe for everyone inside.
13. Exhaust
Your exhaust should be secure, quiet, and not leaking. If you hear unusual rattling or loud noises while driving, it could be loose or damaged. Check the car's undercarriage for rust or loose parts. A damaged exhaust can result in a failed MOT test—and it can be dangerous if fumes enter the vehicle.
14. Exhaust gas
During the MOT, your vehicle's emissions are tested. If there’s thick smoke or unusual smells coming from your exhaust, it could mean trouble. Diesel vehicles may emit a small amount of smoke when starting, but this should not be constant. Regular servicing helps to keep emissions in check. Clean exhaust gas indicates that your car is performing better and is less likely to fail the test.
15. Fuel and Engine Oil
Before your MOT, make sure that your car has enough petrol and engine oil. The tester requires both to check emissions properly. Use your dipstick to check oil levels—just make sure the car’s on level ground; if your levels are low, top them up. It's an easy thing to forget, but without enough fuel or oil, the test may not even start.
16. Headlights and indicators
Make sure all of your lights work, including the dipped beam, full beam, and indicators; turn them on and walk around the vehicle to check. A blown bulb or flickering light can result in a failed MOT test. Also, make sure that the lights are clean and not dimmed due to dirt or damage. Replacing a bulb takes a few minutes and can save you from a retest.
17. Light
In addition to headlights, don't forget about brake lights, reverse lights, number plate lights, and fog lights. Each of them contributes to your car's safety and visibility. If any are out or flickering, replace the bulbs. One of the most common causes of MOT failures is a defective light, which is also one of the easiest to fix at home.
18. Mirrors
Check your wing mirrors and rear view mirror. They should be secure, clear, and without cracks. You need a clear vision of the road behind and to the sides. A broken or loose mirror is enough to fail your MOT. Clean them well, and replace any broken ones. Stick-on mirrors might not pass, so it’s better to get proper replacements if needed.
19. Screenwash
An empty screenwash bottle can cause a car to fail its MOT test. Make sure it's full and the jets are spraying properly. If the washers don’t work, the wipers can’t clear the windscreen, and that’s a safety issue. Topping up takes seconds and allows you to see the road well.
20. steering
Your steering should feel smooth, not loose or heavy. If the wheel shakes, sticks, or makes noises as you turn, something is wrong. A faulty steering system is dangerous and can result in a MOT failure. If your car has power steering, make sure the fluid is topped up; if in doubt, have it checked before the test.
21. Suspensions
Suspension allows your car to handle bumps and keep the ride stable. If your car feels bouncy or knocks over bumpy roads, something is wrong. Press down on each corner of your car; it should bounce once before settling. Too much bounce could indicate worn-out shock absorbers. Suspension issues are more difficult to detect, but they’re a common MOT fail, so it’s worth checking.
22. VIN
Your car's VIN (Vehicle Identification Number) should be easy to read and match the logbook. It's usually found at the bottom of the windscreen or inside the driver's door. If it's missing, scraped off, or does not match your record, there's a problem. It’s a legal ID for your car and something the tester checks during your MOT check.
23. Warning lights
When you start your car, the warning lights should come on briefly before turning off. If any of the lights stays lit while you're driving, such as the airbag, engine, or ABS light, it's a red flag. It informs the tester that there may be an issue. Get any warning lights checked and repaired before your MOT. Ignoring them will not make them go away, and they can lead to an instant failure.
24. Windscreen
A clean, crack-free windscreen allows you to see clearly and helps you pass your MOT. Any chip larger than 10mm in the driver's field of view, or more than 40mm elsewhere, can fail you. Make that the glass is clean, the wipers are properly clearing the screen, and there is no significant damage. Small chips? Get them repaired before they turn into something worse.
What steps should you take to prepare your car for an MOT test?
Before your MOT, give your car a once-over. Check the tyres, lights, brakes, mirrors and seat belts to detect any problems early. Fill up fluids like oil, screenwash, and brake fluid. Make sure that your number plate is clean and readable; clear any warning lights on your dashboard. Don’t forget a Bhp check to understand your engine’s power, use a ULEZ checker if you drive in low-emission zones, and do a car tax check to make sure everything’s up to date. A bit of prep now can save hassle later.
What should you do if your car fails the MOT?
If your car fails its MOT, the garage will provide you with a list of the problems. Some issues, such as a broken bulb, can be minor and easily repaired. Others might be more serious. You can get the repairs done at the same garage or elsewhere. If it is resolved within 10 working days, you can usually get a free or discounted retest. Don’t drive the car if it’s failed with dangerous faults—it’s illegal and unsafe. Get things sorted, and then schedule the retest as soon as possible.
