Each year, millions of vehicles in the UK go through the MOT test—a legal requirement that ensures your car meets essential safety and environmental standards. And every year, a significant number of those vehicles fail due to avoidable issues.
Whether you’re driving a brand-new model or an older car, understanding the most common reasons for MOT failure can help you pass the test the first time. In this guide from your trusted Car Garage MOT experts, we’ll cover the top 10 reasons cars fail MOTs—and how to easily avoid them.
1. Faulty Lights and Indicators
Why Cars Fail:
Blown bulbs, broken indicators, or misaligned headlights are among the most frequent MOT failure causes.
How to Avoid:
Do a quick walk-around before your MOT. Test your headlights, brake lights, reverse lights, indicators, and number plate lights. Replacing a bulb is cheap and easy!
2. Worn or Damaged Tyres
Why Cars Fail:
Tread depth below the legal minimum (1.6mm), bulges, cracks, or uneven wear can cause a fail.
How to Avoid:
Use a tread depth gauge or the “20p test.” Also check for visible damage. If unsure, ask your Car Garage MOT technician to inspect them in advance.
3. Brake Issues
Why Cars Fail:
Low brake fluid, worn pads or discs, or imbalance between sides of the vehicle are common brake-related failures.
How to Avoid:
Have your brakes checked regularly, especially if you notice unusual noises or reduced stopping power. Many MOT garages offer pre-checks.
4. Windscreen Wipers and Washers
Why Cars Fail:
Smearing wiper blades or empty washer fluid can result in a fail due to impaired visibility.
How to Avoid:
Replace worn blades and top up your washer fluid before the test. It’s a 2-minute fix that could save you a fail.
5. Cracked or Obstructed Windscreens
Why Cars Fail:
Chips or cracks in the driver’s line of sight—or stickers that block visibility—can fail your MOT.
How to Avoid:
Repair chips early. Remove anything that might block the driver’s view (e.g., phone holders, decals) before the test.
6. Suspension Problems
Why Cars Fail:
Worn shock absorbers, broken springs, or leaking struts are all common suspension issues spotted during an MOT.
How to Avoid:
Listen for clunks or knocks when driving over bumps. Ask your Car Garage MOT center for a quick suspension check if your ride feels off.
7. Exhaust and Emissions Failures
Why Cars Fail:
Excessive emissions, noisy exhausts, or leaking pipes can lead to a failed MOT—especially for diesel vehicles with faulty DPFs (Diesel Particulate Filters).
How to Avoid:
Keep your engine well maintained and avoid short journeys before the test. A good pre-MOT service can help reduce emission levels.
8. Number Plate Issues
Why Cars Fail:
Illegible, dirty, damaged, or incorrect number plates can be an instant fail.
How to Avoid:
Make sure your plates are clean, secure, and follow the legal format. A quick clean before the test makes all the difference.
9. Warning Lights on the Dashboard
Why Cars Fail:
Dashboard warning lights (airbag, ABS, engine) that remain illuminated after startup can cause a fail under MOT rules.
How to Avoid:
Don’t ignore warning lights. Have them diagnosed and fixed before heading to your MOT appointment.
10. Poor Vehicle Maintenance
Why Cars Fail:
Basic neglect—like low oil levels, loose battery terminals, or dirty mirrors—can lead to multiple minor faults and a cumulative fail.
How to Avoid:
Give your car a basic once-over. Clean it, top up fluids, and ensure all basics are in good condition. Better yet, book a Car Garage MOT pre-check or service combo.
Final Tips to Pass Your MOT First Time
- Book your MOT in advance to avoid the last-minute rush
- Use a trusted Car Garage MOT center with experienced technicians
- Combine your MOT with a basic service for full peace of mind
- Keep records of previous MOT advisories and address them early
Final Thoughts
Failing an MOT can be frustrating—but most issues are simple to fix if caught in advance. Regular maintenance and a pre-test check can save you time, money, and stress.
At our Car Garage MOT center, we help drivers stay road-legal and safe with thorough inspections and expert advice. Book your MOT today and drive away with confidence.
