Top 10 Reasons Cars Fail Their MOT – and How to Avoid Them

When it comes to keeping your car road-legal and safe, the annual MOT test is one date you can’t ignore. Yet, according to the DVSA, nearly 40% of cars fail their MOT at the first attempt — and most for reasons that could have been prevented with a quick pre-check.

At GW Auto Repairs in Carlisle, we carry out Class 4 and Class 7 MOTs every day, so we know exactly what tends to trip people up. Here’s our expert rundown of the top 10 MOT failure points and how to avoid them.

1. Faulty or Damaged Lights

Reason for failure: Nearly 1 in 5 MOT failures are due to blown bulbs, faulty brake lights, or damaged lenses. How to avoid it: Do a quick check before your MOT — test headlights, brake lights, indicators, and number plate lights. Bulbs are cheap, and we can often fit them while you wait.

2. Worn Tyres

Reason for failure: Tyres below the legal tread depth (1.6mm) or with sidewall damage will fail. How to avoid it: Use the 20p coin test — if you can see the outer rim of the coin when inserted into the tread, it’s too low. We offer tyre checks and replacements for all budgets.

3. Brake Issues

Reason for failure: Worn brake pads, discs, or contaminated brake fluid are common problems. How to avoid it: If you notice squealing, grinding, or pulling to one side when braking, book in for a brake inspection before your MOT.

4. Suspension Problems

Reason for failure: Worn or damaged shock absorbers, springs, or linkages reduce handling and safety. How to avoid it: Listen for clunks over bumps and watch for uneven tyre wear. Our technicians can spot suspension issues during a pre-MOT check.

5. Windscreen Wiper & Washer Faults

Reason for failure: Poor visibility due to worn wiper blades or a non-functioning washer system. How to avoid it: Replace wiper blades annually and top up washer fluid.

6. Exhaust & Emissions

Reason for failure: Leaks, corrosion, or emissions above legal limits — especially in diesel vehicles with DPF issues. How to avoid it: If you hear unusual exhaust noise or see excessive smoke, get it checked early.

7. Number Plate Problems

Reason for failure: Damaged, incorrectly spaced, or non-reflective number plates. How to avoid it: Make sure plates are clean, readable, and meet DVSA regulations.

8. Steering Faults

Reason for failure: Excessive play in the steering wheel or worn components. How to avoid it: If steering feels loose or unresponsive, get it checked before test day.

9. Seatbelt Defects

Reason for failure: Frayed belts, faulty buckles, or non-functioning retractors. How to avoid it: Inspect belts for wear and ensure they click securely into place.

10. Warning Lights

Reason for failure: An illuminated ABS, airbag, or engine management light will fail the MOT. How to avoid it: Book a diagnostic check to find and fix the fault before your MOT appointment.

Expert Tip: Book an MOT Pre-Check

A pre-MOT inspection is the easiest way to avoid failure. At GW Auto Repairs, we’ll check your lights, tyres, brakes, and key safety systems — giving you the chance to fix issues before test day.

Book your MOT or pre-check today and drive into your test with confidence.

📞 Call 01228 402500