Common MOT Failures

The annual MOT test is a crucial part of car ownership in the United Kingdom, ensuring that vehicles are safe, roadworthy, and environmentally compliant. While many drivers diligently maintain their cars, a surprising number still find themselves failing this mandatory inspection. Understanding the most common reasons for an MOT failure can save you time, money, and the frustration of a failed test. This article delves into the typical culprits that lead to an MOT rejection, offering insights into preventative measures and what to look out for.

Tyres: The Foundation of Safety

It might not come as a surprise to many, but tyres consistently rank as one of the most frequent causes of MOT failures. The MOT testers are looking for several key aspects regarding your tyres:

• Tread Depth: The legal minimum tread depth in the UK is 1.6mm across the central three-quarters of the tyre's width. Insufficient tread significantly reduces grip, especially in wet conditions, making it a major safety hazard.
• Damage and Wear: Cuts, bulges, or cracks in the tyre sidewall are immediate reasons for failure. Uneven wear patterns can also indicate underlying suspension or alignment issues, which will be flagged.
• Corrosion: Excessive corrosion on the wheel rim, particularly affecting the tyre seal, can lead to a failure.

Regularly checking your tyre pressure and tread depth is a simple yet effective way to avoid this common pitfall. Many garages offer free tyre checks, so take advantage of them.

Braking System: Your Vehicle's Lifeline

The braking system is arguably the most critical safety component of any vehicle. Unsurprisingly, issues with brakes are a leading cause of MOT failures. Testers examine:

• Brake Pad and Disc Wear: Worn-out brake pads and discs significantly reduce braking efficiency. The MOT test checks for minimum thickness and any signs of damage like scoring or warping.
• Brake Fluid Levels: Low brake fluid can indicate a leak in the system or that the pads are severely worn.
• Brake Performance: The vehicle is tested on a rolling road to measure the braking force applied by each wheel. Uneven braking or insufficient stopping power will result in a failure.
• Handbrake Operation: The handbrake (parking brake) must hold the vehicle firmly on a steep incline. A weak handbrake is a common failure point.

Listen for any grinding noises when braking, and be aware of a spongy brake pedal – these can be early indicators of trouble.

Lights: Visibility is Key

Proper functioning lights are essential for both seeing and being seen. Failures related to lighting systems are widespread:

• Headlights: Incorrect aim (too high or too low), faulty bulbs, or damaged casings will cause a failure. The colour of the light is also checked; headlights must emit white light, and rear fog lights red.
• Brake Lights: All brake lights must illuminate when the brake pedal is pressed. A single faulty brake light is enough to fail.
• Indicators: All indicators must flash correctly and at the appropriate rate. Broken or non-functioning indicators are a failure.
• Other Lights: This includes sidelights, rear lights, and number plate lights. Any burnt-out bulb or damaged lens will lead to a fail.

It's a good habit to walk around your car and check all your lights regularly, especially before your MOT is due.

Suspension and Steering: For a Smooth Ride

The components that connect your wheels to the car's body are vital for control and comfort. Issues in the suspension and steering systems are frequent MOT failures:

• Shock Absorbers: Leaking or excessively worn shock absorbers will cause the vehicle to fail.
• Springs: Cracked or weakened springs are a safety concern.
• Ball Joints and Tie Rods: Excessive play or wear in these steering components can lead to a loss of control.
• Wheel Bearings: Worn wheel bearings can cause excessive play and noise, leading to a fail.

Pay attention to any clunking noises when going over bumps or if your steering feels loose or imprecise.

Visibility: Seeing and Being Seen Clearly

Beyond just lights, other aspects of visibility are tested:

• Windscreen: Cracks or chips in the windscreen that are larger than 10mm in the driver's primary field of vision, or chips larger than 40mm elsewhere on the windscreen, will result in a failure.
• Wiper Blades: Ineffective or damaged wiper blades that don't clear the windscreen properly are a failure.
• Washers: The windscreen washer system must be in working order, providing fluid to the screen.

Keep your windscreen clean and address any chips or cracks promptly.

Exhaust Emissions: Environmental Compliance

While less common than some of the mechanical failures, incorrect exhaust emissions are a significant reason for failure, particularly for older diesel vehicles. The test measures:

• CO2 Levels: The amount of carbon dioxide emitted.
• Particulate Matter: Especially relevant for diesel vehicles, testing for soot and other particles.

Regular servicing, including checking and replacing the exhaust system and catalytic converter when necessary, can help ensure your emissions are within the legal limits.

Other Common Failures

Beyond the major categories, several other issues can lead to an MOT failure:

• Bodywork: Sharp edges or projections that could injure pedestrians, or significant structural rust that compromises the vehicle's integrity, can cause a fail.
• Horn: The horn must work correctly and emit a continuous sound.
• Seatbelts: Any damage, wear, or malfunctioning of seatbelts, including the pre-tensioner, will lead to a fail.
• Doors: Doors must open and close correctly from both the inside and outside.
• Fuel System: Leaks in the fuel system are a serious safety hazard and will result in a fail.

Preventative Maintenance: Your Best Defence

The best way to ensure your car passes its MOT is through consistent and proactive maintenance. Here's a summary of key checks you can perform:

Frequently Asked Questions (FAQs)

Q1: Can I drive my car if it fails its MOT?
You can drive your car to a pre-booked MOT test appointment or to a place of repair. Otherwise, it is illegal to drive a vehicle that has failed its MOT test and is not roadworthy.

Q2: How long is an MOT certificate valid for?
An MOT certificate is typically valid for 12 months. You can renew your MOT up to one month before it expires without losing any time on your existing certificate.

Q3: What happens if my MOT expires?
If your MOT expires, you cannot legally drive your car on public roads until it has passed a new MOT test. You could face a fine and penalty points on your licence.

Q4: Can I get an MOT done early?
Yes, you can get your MOT done up to one month (minus one day) before your current MOT expires. The new expiry date will be 12 months from the original expiry date.

Q5: What if my car fails its MOT but is still drivable?
If your car fails its MOT but is still considered drivable, you can usually drive it to a garage for repairs. However, if the failure relates to a dangerous defect (e.g., faulty brakes, steering), you must not drive it until it's repaired.

Conclusion

The MOT test is designed to ensure road safety for everyone. By understanding the most common reasons for failure – particularly tyres, brakes, and lights – and by performing regular checks and maintenance, you can significantly increase your chances of passing. Don't wait until the last minute; a little proactive care can save you a lot of hassle and ensure your vehicle is safe and legal on Britain's roads.