Top 10 Most Common Reasons Cars Fail Their MOT

Every year, nearly a third of all cars fail their initial MOT test. What makes this statistic even more shocking is that many of these failures are due to simple, preventable issues that could have been resolved by the owner in just a few minutes.

Understanding what MOT testers are looking for can save you the stress of a retest and the expense of garage labour rates. Here are the top 10 most common reasons cars fail their MOT and how you can avoid them.

1. Lighting and Signalling Issues (30% of failures)

By far the most common reason for an MOT failure is a blown bulb. According to the DVSA MOT testing data, lighting and signalling defects account for nearly 30% of all initial failures. This covers everything from headlights and indicators to brake lights and number plate bulbs.

How to avoid it: Ask a friend to walk around the car while you test all the lights. Replace any blown bulbs immediately. It's a £2 fix that can save you a £40 MOT retest fee.

2. Suspension and Steering (10% of failures)

Potholes and poor road surfaces take a heavy toll on a car's suspension and steering components. Official figures show that steering and suspension issues account for roughly 10% of fails. Worn shock absorbers, broken coil springs, and leaking suspension fluid are frequent culprits.

How to avoid it: Listen for any knocking or clunking noises when driving over bumps. If the car feels unstable or pulls to one side, have a mechanic inspect the suspension before your test.

3. Brakes (10% of failures)

Brakes are a critical safety component, and the MOT test is rigorous in this area. Worn brake pads, heavily scored or warped discs, and faulty handbrakes cause about 10% of MOT failures, as detailed in the DVSA statistical records.

How to avoid it: Pay attention to your brakes. If you hear squealing or grinding noises, or if the brake pedal feels spongy, get the pads and discs checked. Also, test your handbrake on a steep hill to ensure it holds the car securely.

4. Tyres (10% of failures)

Bald tyres, incorrect tyre pressures, and damaged sidewalls are a massive safety risk. Tyre defects are responsible for around 10% of failures. You can check the exact DVSA statistical datasets to see breakdown details by vehicle type.

How to avoid it: Check the tread depth across the central three-quarters of all four tyres. Look out for nails, screws, bulges, or tears in the rubber.

5. Driver's View of the Road (7% of failures)

This category covers anything that could obstruct your view, including damage to the windscreen, broken wipers, or even items hanging from the rearview mirror. According to DVSA reports, driver visibility issues lead to roughly 7% of failures.

How to avoid it: Remove any dangling air fresheners or sat-navs stuck in the swept area of the wipers. Check the wiper blades for tears and ensure the screenwash is topped up.

6. Exhaust and Emissions (5% of failures)

A leaking exhaust or a car that fails the emissions test will not receive an MOT certificate. Diesel cars with removed or heavily clogged DPFs (Diesel Particulate Filters) will also fail.

How to avoid it: Listen for a blowing noise from the exhaust. If your car is diesel, ensure it gets a regular long run on the motorway to clear out the DPF.

7. Seatbelts and Seats (2% of failures)

A frayed seatbelt or one that doesn't retract properly is an automatic fail. The driver's seat must also lock securely into position.

How to avoid it: Pull all the belts out completely to check for damage, and test that they snap back into place.

8. Bodywork and Structure

Sharp edges caused by rust or accident damage pose a risk to pedestrians. Excessive corrosion on structural components or within 30cm of a steering, suspension, or seatbelt mounting point is a serious failure.

9. Number Plates

Your number plates must be securely attached, completely legible, and conform to the standard UK font and spacing regulations. Fancy or tinted plates will result in a failure.

10. Fluid Leaks

A major leak of engine oil, power steering fluid, or brake fluid that creates a pool on the floor within five minutes of idling is an MOT failure.

By keeping an eye out for these 10 common issues, you can dramatically improve your chances of passing your MOT the first time.