MOT Failures: Common Reasons & How to Avoid Them

The MOT test, or Ministry of Transport test, is a crucial annual inspection for vehicles in the UK that are three years or older. Its primary purpose is to ensure that your car meets the minimum road safety and environmental standards. While many drivers take their car for granted until it's time for the MOT, understanding the common reasons for failure can save you time, money, and considerable stress. This article delves into the most prevalent MOT failure points and provides actionable advice to help you keep your vehicle in tip-top condition and sailing through its annual inspection.

Understanding the MOT Test

Before diving into failure reasons, it's helpful to understand what the MOT test actually checks. It's not a test of the mechanical condition of the engine, gearbox, clutch, or other major components. Instead, it focuses on specific areas critical for roadworthiness and emissions. These include:

• Body and Structure: Checks for excessive corrosion, sharp edges, or damage that could affect structural integrity or pose a danger to occupants or other road users.
• Fuel System: Examines for leaks or improper connections.
• Exhaust Emissions: Ensures the vehicle meets the required emission standards.
• Visibility: Assesses the condition of the windscreen, wipers, and washers.
• Lights: Checks all lights, including headlights, taillights, brake lights, and indicators, for correct operation and alignment.
• Brakes: A critical component, this includes checking the effectiveness of the braking system, including the condition of brake pipes, hoses, and the parking brake.
• Tyres and Wheels: Evaluates tyre tread depth, condition, and whether wheels are securely fitted.
• Seatbelts: Checks for the presence, operation, and condition of all seatbelts.
• Doors: Ensures doors open and close correctly and latches securely.
• Horn: Verifies that the horn works and is suitable for the vehicle.
• Steering and Suspension: Assesses the condition of steering components, shock absorbers, and suspension parts.
• Windscreen Wipers and Washers: Checks for effective operation.
• Registration Plates: Ensures plates are present, legible, and correctly fitted.

Top Reasons for MOT Failure

While a car can fail for a multitude of reasons, some issues are far more common than others. Being aware of these can help you proactively maintain your vehicle and prevent a failed MOT.

1. Lighting Issues

Faulty or incorrectly aimed lights are a very common reason for failure. This includes burnt-out bulbs, cracked casings, or lights that are the wrong colour. Ensure all your lights, including brake lights, indicators, and headlights, are working correctly and are properly aligned. A simple check before your MOT can save you a retest.

Key Points:

• Headlight aim (too high or too low).
• All bulbs functioning (headlights, taillights, brake lights, indicators, reverse lights, number plate lights).
• Correct colour of lights (e.g., indicators must be amber).
• Cracked or damaged light casings.

2. Tyre Problems

Tyres are another frequent culprit. The legal minimum tread depth for car tyres in the UK is 1.6mm across the central three-quarters of the tread width. However, tyres can fail for reasons beyond just tread depth. Cuts, bulges, exposed cords, or damage to the sidewalls will also result in a fail. Ensure your tyres are the correct type and pressure for your vehicle and that they are free from damage.

3. Brake System Defects

The braking system is paramount for safety, and any fault here is taken very seriously. This can include worn brake pads and discs, leaking brake fluid, corroded brake pipes, or a malfunctioning parking brake. Regular checks of your brake fluid level and the condition of your brake pads and discs are essential. If you notice any sponginess in the brake pedal or unusual noises when braking, get it checked immediately.

Brake Checks:

• Brake Pad and Disc Wear: Look for a minimum thickness and check for scoring or warping.
• Brake Fluid: Ensure the level is correct and the fluid is clean, not contaminated.
• Brake Pipes and Hoses: Check for corrosion, leaks, or damage.
• Parking Brake: Ensure it holds the vehicle effectively on a gradient.

4. Windscreen and Wiper Issues

Visibility is key. A cracked or significantly scratched windscreen can cause an MOT fail, especially if it obstructs the driver's view. The MOT manual specifies that chips or cracks larger than 10mm in the driver's line of sight, or larger than 40mm elsewhere on the windscreen, will result in a fail. Similarly, windscreen wipers that don't clear the screen effectively or washers that don't spray water will also lead to a fail.

5. Suspension and Steering Components

Problems with the suspension and steering can compromise a vehicle's handling and stability. This includes worn ball joints, damaged shock absorbers, loose steering components, or excessive play in the steering system. Any signs of leaks from shock absorbers or significant wear in these areas will likely result in a failure.

6. Exhaust Emissions

With increasing environmental awareness, emissions are a significant part of the MOT. If your car's exhaust emissions exceed the set limits, it will fail. This can be due to a faulty catalytic converter, issues with the engine management system, or even simple things like a damaged or leaking exhaust system. Regular servicing can help keep your emissions in check.

7. Body and Structural Damage

While less common for newer cars, older vehicles might fail due to excessive corrosion. The MOT test checks for structural integrity, meaning any rust holes or sharp edges on the bodywork that could pose a danger will lead to a fail. This includes areas like wheel arches, sills, and chassis components.

8. Seatbelts and Airbags

All seatbelts must be present, correctly fitted, and fully functional. This means they should retract smoothly and latch securely. Any damaged or malfunctioning seatbelts will cause a fail. While airbags aren't explicitly tested for deployment, if the airbag warning light remains illuminated on the dashboard, this indicates a fault within the system and will result in a failure.

9. Registration Plates

Simple, yet often overlooked. The registration plates must be correctly displayed, legible, and securely fitted. Any damage that makes them unreadable, or if they are missing, will result in a fail.

Preventative Measures and Tips

The best way to avoid an MOT failure is through regular maintenance and pre-MOT checks. Here are some tips:

• Regular Servicing: Don't wait for the MOT to find problems. Regular servicing by a qualified mechanic will help identify and fix issues before they become MOT failures.
• Visual Inspection: Before taking your car to the test centre, do a quick walk-around. Check your lights, tyres, and windscreen for any obvious damage or faults.
• Check Tyre Tread: Use a tyre tread depth gauge or a 20p coin to check your tyre tread. If the outer band of the coin is visible when inserted into the tread grooves, your tyres may be below the legal limit.
• Test Your Lights: Turn on all your lights and walk around the car to ensure they are all working and appear correct.
• Check Wipers and Washers: Ensure your wipers clear the screen effectively and the washers spray.
• Know Your Responsibilities: Familiarise yourself with the basic MOT requirements. Many garages offer pre-MOT checks, which can highlight potential issues.

What Happens After a Failed MOT?

If your car fails its MOT, it is illegal to drive it on the road unless you are driving it to a pre-booked appointment for repair or to a pre-booked MOT test appointment. You will receive a 'Refusal of an MOT Test Certificate' (VT30) outlining the reasons for failure. The vehicle can be repaired and retested. If the retest is carried out within 10 working days at the same test centre, only specific items will be re-checked, often meaning a partial fee or no fee at all, depending on the original failure and the repairs made. If you take it elsewhere or longer than 10 days, it will be a full retest.

Common Questions About MOT Failures

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

A1: You can only drive your car to a pre-booked repair appointment or a pre-booked MOT test appointment. Otherwise, it is illegal to drive an unroadworthy vehicle.

Q2: How much does an MOT cost?

A2: The maximum fee for an MOT is set by the government. For cars, it's currently £54.85. Garages may charge less, but cannot charge more than the maximum fee.

Q3: What if my car is too old for the MOT?

A3: The MOT test applies to vehicles that are three years old or older. Once a vehicle reaches this age, it requires an annual MOT inspection.

Q4: Does an MOT check the engine and gearbox?

A4: No, the MOT test does not check the mechanical condition of the engine, gearbox, clutch, or other major mechanical components. It focuses on road safety and emissions.

Q5: What is the minimum tyre tread depth for an MOT?

A5: The legal minimum tyre tread depth for cars in the UK is 1.6 millimetres across the central three-quarters of the tread width.

Conclusion

The MOT test is a vital safeguard for road safety and the environment. By understanding the common reasons for failure and adopting a proactive approach to vehicle maintenance, you can significantly increase your chances of passing the test first time. Regular checks, prompt attention to any warning signs, and adherence to recommended servicing schedules will not only help your car pass its MOT but also ensure it remains safe and reliable for everyday use. Don't let an MOT failure be a surprise; be prepared and keep your vehicle roadworthy.