10 Common Reasons Cars Fail MOT and How to Avoid Them
Every year, millions of UK drivers are surprised to learn their car has failed its MOT. According to DVSA data, around 30% of vehicles fail the MOT test first time. The good news? Most failures are down to simple issues that could easily be fixed before the test.
Here are the 10 most common reasons cars fail MOT — and what you can do to avoid them.
1. Tyres Below the Legal Tread Depth
UK law requires at least 1.6mm tread depth across the central three-quarters of the tyre.
Worn, damaged, or mismatched tyres are among the top failure causes.
Fix it: Use the 20p coin test or ask your local garage for a free tyre check.
2. Faulty Lights and Indicators
Headlights, brake lights, hazard lights, and number plate bulbs must work properly.
Incorrect headlamp alignment is another common fault.
Fix it: Check your lights before the test. Replacement bulbs cost just a few pounds.
3. Brake Issues
Worn brake pads, discs, or an ineffective handbrake will cause an instant fail.
Fix it: Get brakes checked regularly — squeaking or grinding are warning signs.
- Suspension Wear
Leaking, broken, or worn suspension parts are frequently spotted during MOTs.
Fix it: If your car feels bouncy or uneven, book a check before your MOT.
5. Windscreen and Wipers
- Cracks larger than 10mm in the driver’s view or 40mm elsewhere will cause failure.
- Worn wipers that don’t clear the screen are also a fail.
Fix it: Replace damaged wiper blades and repair chips early.
6. Exhaust and Emissions
- Excessive smoke or emissions beyond legal limits will fail.
- Loud or leaking exhausts are also flagged.
Fix it: Service your car regularly, especially diesel filters and catalytic converters.
7. Steering Problems
Excessive free play, power steering leaks, or worn steering components are common issues.
Fix it: If the steering feels loose or pulls to one side, get it inspected early.
8. Seatbelt Defects
Seatbelts must be secure, undamaged, and able to lock properly.
Fix it: Test each belt before your MOT and replace faulty ones immediately.
9. Registration Plate Issues
Plates must be secure, readable, and correctly spaced. Dirty or faded plates can lead to failure.
Fix it: Clean plates before the test and replace cracked or illegal ones.
10. Fluid Leaks
Oil, coolant, or fuel leaks are taken seriously as they pose a safety risk.
Fix it: If you notice puddles under your car, get it repaired before booking your MOT.
How to Prevent MOT Failures
- Book a pre-MOT check at a local garage.
- Do simple DIY inspections (tyres, lights, wipers, fluids).
- Service your car annually to catch issues early.
For a full breakdown of everything garages inspect during the test, see our MOT test checklist
Final Word
Most MOT failures are caused by tyres, lights, or simple maintenance issues. A few quick checks before your test could save you time, stress, and money.
Ready to stay road-legal? Book your MOT test near you today and avoid these common pitfalls. TyreSavings.
FAQs About MOT Failures
Q1: What happens if my car fails its MOT?
You’ll receive a failure certificate (VT30). You cannot drive until repairs are completed, except to and from the garage. If you need to get retested quickly, check our guide on finding a same day MOT near you
Q2: Can I get a free MOT retest?
Yes — if you leave the car at the test centre for repair or return within 10 working days for specific failures.
Q3: What are the most expensive MOT failures?
Major repairs often include brakes, suspension, and emissions systems.
Q4: Is there a grace period after an MOT failure?
No. If your MOT has expired, you can’t legally drive until it passes again.