A faulty bulb. A worn tyre. A low washer bottle. These might not seem like deal-breakers, but they can all lead to a failed MOT certificate and unexpected repair costs.
So, what should you look out for before booking your test? Here are the top 5 warning signs your vehicle might not pass its MOT—and the smart steps you can take to fix things ahead of time.
1. Dashboard Warning Lights
That blinking light on your dashboard that you’ve been ignoring for weeks? It could spell instant failure.
If any warning lights related to the engine, airbags, brakes, ABS, or emissions systems are illuminated during your MOT, the car will almost certainly fail—regardless of whether it’s driving fine.
Why? Because warning lights signal a potential fault that affects either safety or environmental standards.
✅ What to do:
- Book a diagnostic scan before the MOT.
- Even if the issue is just a faulty sensor or a reset-needed system, sorting it out early can save you time and hassle.
2. Worn, Bald, or Damaged Tyres
Your tyres might look okay at first glance, but MOT testers look closer—and they don’t miss a thing. Tread depth must be at least 1.6mm across the central three-quarters of each tyre. Any bulges, cracks, or uneven wear patterns can also lead to an immediate fail.
Driving with worn tyres isn’t just risky—it’s illegal.
✅ What to do:
- Use the 20p test: Insert a 20p coin into the tread. If you can see the outer rim of the coin, your tread is likely too shallow.
- Check for sidewall damage, uneven wear, and ensure tyres are inflated to the recommended pressure.
3. Faulty or Missing Lights
MOT testers will check all external lights—headlights, brake lights, reversing lights, indicators, fog lamps, and even number plate bulbs.
If:
- A bulb is out,
- The light is misaligned,
- Or it emits the wrong colour (e.g., white instead of yellow for indicators),
…your vehicle won’t pass.
✅ What to do:
- Test your lights the night before: park near a wall or garage door and turn them on to check brightness and alignment.
- Ask a friend to help check brake and reverse lights.
- Keep spare bulbs in your glovebox—it’s an easy fix.
4. Poor Wipers or Empty Washer Bottle
It might sound ridiculous, but a streaky windscreen or empty washer bottle is enough to fail your MOT. Visibility is a key safety factor, and testers will check that both the wipers clear the screen effectively and that washers spray fluid properly.
✅ What to do:
- Top up your washer fluid—it costs pennies and takes minutes.
- Replace worn or noisy wiper blades, especially if they smear or skip. Most can be swapped at home without tools.
5. Strange Noises from Suspension or Steering
Hearing clunks, squeaks, or knocks when turning or going over speed bumps? These are often signs of worn suspension, ball joints, or steering components—all of which are critical for safe driving.
MOT testers will check for excessive play or noise in these systems. If anything feels loose or unresponsive, it’s a fail.
✅ What to do:
- Don’t ignore unusual handling or noises—book a pre-MOT inspection or ask your mechanic to check things over.
- Replacing a single worn part early is usually far cheaper than repairing more serious damage later.
? Bonus Tips: How to Prepare for Your MOT
- ✅ Clean your number plates—obscured plates can result in failure.
- ✅ Empty your boot—a cluttered car can prevent full access during inspection.
- ✅ Check seatbelts—they should click and retract fully without fraying.
- ✅ Test your horn—if it doesn’t work, that’s another fail.
A Little Attention Can Go a Long Way
Most MOT-check failures are preventable with basic car care and a quick pre-check. Don’t wait until the day of the test to find out your brake light’s gone or your washer jet is blocked.
If you’re ever unsure, book a pre-MOT check—many garages offer these for free or at a low cost. It gives you a chance to catch and fix minor problems before they cost you time, money, and stress.
Passing your MOT doesn’t have to be a gamble. With a few checks and small fixes, you’ll stay road-legal—and drive away with peace of mind.
