Top 10 Reasons Cars Fail Their MOT
An MOT checks whether your vehicle meets the minimum legal standards for road safety and environmental performance.
Many MOT failures are caused by simple issues that could have been spotted before the test. Checking your car before its MOT can reduce the chance of failure and help you avoid extra repair costs.
Here are 10 of the most common reasons cars fail their MOT.
- Faulty lights and indicators
Lighting problems are one of the most common MOT failure reasons.
Your car can fail if any required light is not working properly, including:
- Headlights
- Brake lights
- Indicators
- Rear lights
- Number plate lights
- Fog lights
Before your MOT, turn on each light and check that it works.
- Tyres below the legal tread depth
Your tyres must meet the legal minimum tread depth.
For cars in the UK, the legal minimum is 1.6mm across the central three-quarters of the tyre tread and around the full circumference.
Your car may fail its MOT if tyres are worn, damaged, underinflated or showing cords.
- Brake problems
Brakes are a major part of the MOT test.
A car can fail for:
- Worn brake pads
- Weak braking performance
- Brake imbalance
- Damaged brake discs
- Handbrake issues
- Brake warning lights
If your brakes feel weak, noisy or uneven, get them checked before the MOT.
- Suspension defects
Suspension problems are another common MOT failure reason.
Signs of suspension issues include knocking noises, uneven tyre wear, poor handling or the car sitting lower on one side.
The MOT tester will check components such as springs, shock absorbers and suspension arms.
- Windscreen damage
A cracked or chipped windscreen can cause an MOT failure if it affects the driver’s view of the road.
Damage in the driver’s line of sight is treated more seriously than damage elsewhere on the windscreen.
Get chips repaired early before they spread.
- Visibility problems
The driver must have a clear view of the road.
Your car may fail if:
- Windscreen wipers are damaged
- Washer fluid does not spray properly
- Mirrors are missing or insecure
- The windscreen is excessively dirty or blocked
- Stickers or objects obstruct the driver’s view
Top up your screenwash and check your wipers before the test.
- Steering issues
The MOT includes checks on steering condition and operation.
A car may fail if there is excessive play, stiffness, fluid leaks, damaged steering components or warning lights related to the steering system.
If the steering feels heavy, loose or unusual, have it inspected.
- Exhaust and emissions failures
Your car must meet emissions standards for its age and fuel type.
Common issues include:
- Excessive exhaust smoke
- Exhaust leaks
- Faulty catalytic converter
- Diesel particulate filter problems
- Engine management warning lights
A poorly maintained engine is more likely to fail on emissions.
- Registration plate problems
Your number plates must be secure, readable and correctly formatted.
Your car can fail if the plates are cracked, dirty, incorrectly spaced, badly lit or using illegal fonts.
Clean your plates and check the number plate lights before the MOT.
- Seatbelt defects
Seatbelts are checked for safety and correct operation.
An MOT failure can happen if seatbelts are damaged, frayed, not locking properly or warning lights are showing on the dashboard.
Check that each seatbelt pulls out, clips in and retracts correctly.
How to avoid failing your MOT
You cannot guarantee a pass, but you can reduce the risk by doing simple checks before the test:
- Check all lights
- Check tyre tread and pressure
- Top up screenwash
- Check wipers
- Clean mirrors and number plates
- Listen for brake or suspension noises
- Check warning lights on the dashboard
- Remove anything blocking the driver’s view
These checks only take a few minutes and can prevent avoidable failures.
Find an MOT garage near you
TheGarageLocator helps you find local garages for MOTs, servicing and repairs.
You can compare garage services, check profiles and request a booking online.
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