Why Cars Fail Their MOT: The Top Reasons (and How to Avoid Them)

For many drivers, an MOT can feel like a stressful unknown. Will it pass? Will it fail? And if it does fail, how much will it cost to put right?

At Foster & Heanes, we carry out MOTs every day across our Fleet and Dogmersfield locations, and we see the same issues causing failures time and time again. The good news? Most MOT failures are avoidable with a little awareness and basic maintenance.

Here’s a breakdown of the most common reasons cars fail their MOT - and what you can do to avoid them.

1. Lighting & electrical faults

The most common MOT failure in the UK.

This includes:

• Blown bulbs
• Brake lights not working
• Indicators flashing too fast or not at all
• Number plate lights failing
• Headlights incorrectly aligned

How to avoid it:

Do a quick walk-around check every few weeks, especially before your MOT. Ask someone to press the brake pedal while you check the rear lights, and replace any blown bulbs promptly.
A single failed bulb can fail the entire MOT.

2. Tyres below legal tread depth

Tyres must have at least 1.6mm of tread across the central three-quarters of the tyre.

Common issues include:

• Bald tyres
• Uneven wear
• Cuts, bulges or exposed cords

How to avoid it:

Check tyre tread regularly using a gauge or a simple 20p coin test. If wear looks uneven, it may point to alignment or suspension issues that should be checked before your MOT.

3. Brake problems

Brakes are a critical safety component, so even minor issues can result in failure, including:

• Worn brake pads or discs
• Binding brakes
• Imbalanced braking performance
• Warning lights illuminated

How to avoid it:

Listen for squealing or grinding noises and pay attention to changes in braking performance. Regular servicing helps identify brake wear long before it becomes an MOT failure.

4. Suspension & steering issues

Suspension faults often go unnoticed by drivers but are common MOT failures.

• Typical problems include:
• Worn shock absorbers
• Broken springs
• Excessive movement in steering components

How to avoid it:

If your car feels bouncy, unstable, or pulls to one side, get it checked. These symptoms often point to suspension wear that can be resolved before MOT time.

5. Warning lights on the dashboard

If a warning light is illuminated — especially for:

• Engine management
• ABS
• Airbags
• Traction control

Your car will almost certainly fail its MOT if any of these are illuminated.

How to avoid it:

Don’t ignore warning lights. A quick diagnostic check can identify and fix issues early, often at a lower cost than leaving them unresolved.

6. Exhaust & emissions failures

Emissions testing is stricter than ever. Failures are often caused by:

• Exhaust leaks
• Faulty sensors
• Engine running inefficiently
• DPF issues on diesel vehicles

How to avoid it:

Regular servicing keeps engines running efficiently and helps prevent emission-related failures. If your car struggles on short journeys, it may benefit from longer runs to help clear filters.

7. Windscreen, wipers & washers

Simple but often overlooked, issues include:

• Cracked windscreens in the driver’s line of sight
• Worn or split wiper blades
• Washer jets not working or empty

How to avoid it:

Replace wiper blades annually, top up screen wash regularly, and address windscreen chips before they spread.

How to reduce the risk of MOT failure

The easiest way to avoid an MOT fail is to:

• Keep up with regular servicing
• Address small issues early
• Book a pre-MOT check
• Avoid leaving your MOT until the last minute

At Foster & Heanes, we can identify potential issues before your test, saving time, stress, and unnecessary costs.

Book Your MOT with Foster & Heanes

We offer MOT testing for all makes and models, including light commercial vehicles, at our trusted local branches:

Dogmersfield
Fleet – Hesters
Fleet – VW Autos
Fleet – Alfanatic

✔ Fully licensed MOT bays
✔ Experienced technicians
✔ Free re-tests within 10 days (if applicable)
✔ Honest advice with no pressure

Call 01252 615657 or book online to secure your MOT appointment and stay road-legal with confidence.

Foster & Heanes - Trusted MOTs, Servicing & Repairs in Fleet & Dogmersfield

Experienced Technicians | All Makes & Models | Local & Reliable