Common MOT Failures Revealed

The annual MOT test is a crucial part of vehicle ownership in the UK, ensuring that cars on the road meet essential safety and environmental standards. While many drivers breeze through their MOT with flying colours, a significant number of vehicles fail each year. Understanding the most common reasons for these failures can save you time, money, and the hassle of unexpected repairs. This guide delves into the typical culprits of MOT failure, offering insights and advice to help you keep your vehicle in tip-top condition and pass with ease.

The Big Offenders: Top MOT Failure Categories

The Driver and Vehicle Standards Agency (DVSA) regularly publishes data on MOT test results, highlighting the areas where cars most frequently fall short. While specific failures can vary, certain categories consistently appear at the top of the list. These are often related to fundamental safety aspects of your vehicle.

1. Lighting Equipment

This is, by far, one of the most common reasons for an MOT failure. Faulty or incorrect lighting can significantly impact your ability to see and be seen, especially during adverse weather conditions or at night. This category includes:

• Headlights: Not working, incorrectly aimed (too high or too low), or the wrong type of bulb fitted. Ensure your headlights are correctly aligned and that you're using the appropriate bulbs for your vehicle.
• Brake Lights: One or more brake lights not illuminating, or a faulty high-level brake light.
• Indicator Lights: Indicators not flashing correctly, the wrong colour, or not working at all.
• Number Plate Lights: Essential for identifying your vehicle, these must be working and emitting a white light.

A simple check of all your lights before your MOT can prevent this common failure. Get a friend to help you check brake lights and indicators while you operate them.

2. Tyres

Tyres are your vehicle's only contact with the road, making their condition paramount for safety. The MOT test scrutinises tyres for several issues:

• Tread Depth: The legal minimum tread depth in the UK is 1.6mm across the central three-quarters of the tyre's breadth. However, many testers will fail tyres with tread approaching this limit, especially if it's uneven. Consider replacing tyres when the tread reaches 3mm for optimal safety.
• Damage: Cuts, bulges, or cracks on the tyre sidewalls or tread can lead to a failure.
• Incorrect Fitment: Tyres that are the wrong size or type for your vehicle, or mismatched tyres on the same axle, will also result in a fail.
• Inflation Pressure: While not a direct failure point, under-inflated tyres can contribute to uneven wear and affect handling, potentially leading to other issues.

Regularly inspect your tyres for wear and damage, and ensure they are inflated to the correct pressure as recommended in your vehicle's handbook. Tyre condition is critical.

3. Brakes

As you might expect, the braking system is a major component of the MOT test. Any issues that compromise braking performance or efficiency will lead to a fail:

• Brake Fluid: Low brake fluid levels or contaminated fluid can indicate a leak or a problem within the system.
• Brake Pad and Disc Wear: Worn brake pads or discs below the minimum thickness limits are a serious safety hazard.
• Brake Performance: The MOT test includes a roller brake test to measure the efficiency of your braking system. Significant differences in braking force between wheels on the same axle, or a general lack of braking power, will result in a fail.
• Parking Brake: The handbrake (or electronic parking brake) must hold the vehicle securely on the test ramp.

Listen for any unusual noises when braking and pay attention to the feel of the brake pedal. Promptly address any concerns regarding your brakes.

4. Suspension

A vehicle's suspension system is vital for handling, stability, and ride comfort. The MOT test checks for wear and tear that could affect these aspects:

• Shock Absorbers: Leaking or excessively worn shock absorbers will cause a fail.
• Springs: Broken or corroded springs are a safety risk.
• Ball Joints and Bushings: Excessive wear in suspension joints and bushings can lead to poor handling and a fail.
• Wheel Bearings: Loose or noisy wheel bearings are another common failure point.

If you notice knocking sounds from your suspension or your car pulls to one side, it's worth getting it checked before your MOT.

5. Steering

Like the suspension, the steering system is crucial for control. Issues here can be extremely dangerous:

• Power Steering: Leaks or excessive play in the power steering system.
• Steering Rack and Joints: Wear or damage to the steering rack, track rod ends, or other steering components.
• Excessive Play: Any significant looseness in the steering wheel that isn't accounted for by normal wear.

Your steering needs to be precise and responsive.

Other Common Failures

Beyond these major categories, several other issues frequently cause MOT failures:

• Windscreen: Cracks or chips in the windscreen that obstruct the driver's view (larger than 10mm in the driver's direct line of sight, or larger than 40mm in the rest of the swept area).
• Wipers and Washers: Wipers not clearing the windscreen effectively or washer fluid not being sprayed.
• Exhaust Emissions: Your vehicle must meet specific emissions standards. A faulty catalytic converter or other engine management issues can cause a fail.
• Horn: The horn not working when operated.
• Bodywork: Significant corrosion or sharp edges that could be a danger to other road users.
• Fuel System: Leaks in the fuel lines or tank.

Preventative Maintenance: Your Best Defence

The best way to avoid an MOT failure is through regular and proactive maintenance. Don't wait for the annual test to discover a problem. Here are some key areas to focus on:

Regular Servicing

A full service typically includes checks on many of the components that are tested during the MOT. Following your manufacturer's recommended service schedule is highly advisable. This can help identify and rectify minor issues before they become major, costly failures.

Pre-MOT Checks

Even if you don't opt for a full service, a quick pre-MOT check can be invaluable. This doesn't need to be done by a professional. You can check:

• All lights are working and clean.
• Tyre tread depth and condition.
• Windscreen for damage and ensure washers and wipers work.
• Horn functionality.
• Mirrors are secure and not cracked.

Listen and Feel

Your car will often give you warning signs. Strange noises, changes in handling, warning lights on the dashboard, or unusual smells are all indicators that something might be wrong and could be an MOT failure point. Listen to your car.

MOT Test Categories Explained

The MOT test categorises defects into three types:

• Minor: The vehicle will pass, but the defect should be repaired soon.
• Major: The vehicle will fail. The defect must be repaired immediately.
• Dangerous: The vehicle will fail. The defect must be repaired immediately, and driving the vehicle is prohibited until it's fixed.

It's important to understand these categories. A 'major' or 'dangerous' defect will result in an automatic fail, even if it's a seemingly small issue.

Common MOT Failure Rates: A Comparative Look

While precise figures fluctuate, the following table gives a general idea of the common failure rates for the most frequent issues. These are based on typical annual MOT data.

Note: These percentages are approximate and can vary year on year.

Frequently Asked Questions (FAQs)

Q1: Can I drive my car if it fails its MOT?

You can drive your car if it fails its MOT only if the existing MOT certificate is still valid and the new failure does not result in a 'dangerous' defect. If the new failure is classified as 'dangerous', you cannot drive the vehicle until it is repaired. It's always best to get the repairs done immediately.

Q2: How long do I have to get repairs done after failing my MOT?

If your car fails its MOT, you typically have 10 working days to get the necessary repairs done and have a partial re-test. If you leave the car at the test centre for repair, it may be eligible for a free partial re-test. If you take it elsewhere, it will be considered a new test.

Q3: What happens if my MOT has expired?

You cannot legally drive your car on public roads if its MOT certificate has expired, unless you are driving it to a pre-booked MOT test appointment. Driving without a valid MOT can result in a fine and penalty points on your licence.

Q4: Can I check my car's MOT history online?

Yes, you can check your car's MOT history online using your vehicle's registration number on the official government website. This will show you past MOT test results, including advisories and failures.

Conclusion

The MOT test is a vital safety check, and understanding the common reasons for failure is the first step towards ensuring your vehicle is compliant and safe. By performing regular checks, addressing minor issues promptly, and keeping up with maintenance, you can significantly increase your chances of passing your MOT test with flying colours. Remember, a well-maintained vehicle is not only safer but also more reliable and economical to run. Don't let a preventable MOT failure disrupt your driving life!

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