The Most Common MOT Failures in the UK — And How to Avoid Them

Every year, millions of cars in the UK go through the MOT test — and roughly 36% fail on the first attempt. That might sound alarming, but the reality is that most failures are for minor, preventable issues that could have been spotted and fixed before the test.

A few minutes spent checking the basics before your MOT can save you the cost of a retest, the inconvenience of being without your car, and potentially hundreds of pounds in garage labour charges for simple fixes you could have done yourself.

Top 10 MOT Failure Reasons (DVSA Data)

1. Lighting and Signalling (~30% of Failures)

By far the most common reason for MOT failure. This includes blown headlight bulbs, faulty brake lights, defective indicators, number plate lights, fog lights, and misaligned headlamps.

How to avoid it: Before your test, check every light on the car. Turn on the headlights (dipped and main beam), indicators, brake lights (get someone to help or reverse near a window), fog lights, reverse lights, and number plate lights. Replace any blown bulbs — most are £5–£10 from a motor factor and take minutes to fit.

2. Suspension (~15% of Failures)

Worn shock absorbers, broken springs, damaged anti-roll bar links, and worn bushes are all common suspension failures. These are harder to spot yourself but symptoms include excessive bouncing, clunking noises over bumps, and uneven tyre wear.

How to avoid it: Push down firmly on each corner of the car and release. If the car bounces more than once before settling, the shock absorbers may be worn. Listen for knocking or clunking when driving over speed bumps. If in doubt, ask a garage to do a visual inspection before the MOT.

3. Brakes (~10% of Failures)

Worn brake pads, scored brake discs, seized calipers, and imbalanced braking are common. The MOT includes a rolling road brake test that measures the performance of each wheel.

How to avoid it: Listen for squealing or grinding when braking. Check brake fluid level (it should be between the min and max marks). If you can see through the wheel spokes, check the thickness of the brake pads — they should have at least 3mm of material remaining.

4. Tyres (~8% of Failures)

The legal minimum tread depth in the UK is 1.6mm across the central three-quarters of the tyre. The MOT also checks for cuts, bulges, exposed cord, and uneven wear. Tyres with different speed ratings on the same axle can also fail.

How to avoid it: Use a 20p coin to check tread depth — if the outer band of the coin is visible when inserted into the tread, the tyre is below 1.6mm and needs replacing. Inspect the sidewalls for bulges or cracks. Ensure matching tyres on each axle.

5. Driver’s View / Windscreen (~7% of Failures)

Chips or cracks in the windscreen can cause a failure depending on their size and location. A crack larger than 10mm in the driver’s central zone (a 290mm-wide area directly in front of the steering wheel), or larger than 40mm anywhere else in the swept area, is a fail.

How to avoid it: Get chips repaired early before they spread into cracks. Many insurance policies cover windscreen repair for free (no excess). Also ensure nothing is obscuring the driver’s view — including stickers, air fresheners, or satnav mounts in the swept area.

6. Exhaust and Emissions (~7% of Failures)

This covers exhaust leaks, catalytic converter function, and emissions levels. Since the 2018 MOT changes, diesel vehicles face stricter emissions testing including visible smoke and DPF checks.

How to avoid it: If your car smokes on start-up or has a dashboard emissions warning light, address these before the test. For diesels, take the car for a 20–30 minute motorway drive before the MOT to regenerate the DPF. Any dashboard warning light related to emissions is an automatic fail.

7. Steering (~5% of Failures)

Excessive play in the steering, worn track rod ends, damaged gaiters, and power steering fluid leaks are common failures. These are not easily checked at home.

How to avoid it: If the steering feels loose, wanders at speed, or you hear knocking when turning, have it inspected before the MOT. Check power steering fluid level if applicable.

8. Bodywork and Corrosion (~4% of Failures)

Sharp edges from rust or damage that could injure someone, and structural corrosion within 30cm of key mounting points (suspension, steering, brakes, seatbelt mounts) will cause a failure.

How to avoid it: Check wheel arches, sills, and the underside of doors for bubbling paint or rust. Look underneath the car near suspension mounts. If you spot structural rust, have a garage assess whether it is within MOT-relevant areas.

Final Thoughts

The majority of MOT failures are entirely preventable. A 15-minute walk-around checking lights, tyres, wipers, and the windscreen before your test can save you the hassle and expense of a failure. For the items you cannot check yourself — suspension, brakes, steering — consider booking a pre-MOT inspection at a garage, which typically costs £20–£30 and can highlight issues before the official test.

MOT failure data is based on published DVSA statistics. Exact percentages vary year to year. Always consult a qualified mechanic for specific vehicle concerns.