What are the most common reasons for MOT failure?

The Ministry of Transport test, commonly known as the MOT, is an annual vehicle safety test required in the United Kingdom for most vehicles over three years old. It ensures that vehicles meet road safety and environmental standards. Despite the importance of the MOT test, many vehicles fail their first attempt, often due to common and preventable issues. In this blog post, Car & Bike Magic helps explore the most frequent reasons for MOT failure, providing detailed insights into each cause and offering advice on how to avoid these pitfalls.

Lighting and Signalling

One of the most common reasons for MOT failure is issues with vehicle lighting and signalling. These include faulty headlights, brake lights, indicator lights, and rear lights. Lights must be fully operational and correctly aligned to pass the MOT test. Over time, bulbs can burn out, and connections can become loose or corroded. Regularly checking all lights and replacing any faulty bulbs can prevent this type of failure. Additionally, ensuring that the lights are clean and free from damage will help maintain visibility and signaling efficiency.

Tyres and Wheels

Tyres are a critical component of vehicle safety, and their condition is a frequent cause of MOT failure. Tyres must have a minimum tread depth of 1.6mm across the central three-quarters of the tyre, around its entire circumference. Worn or damaged tyres, including cuts, bulges, or other defects, will result in a failed MOT. Proper tyre maintenance includes regular checks for tread depth, ensuring correct tyre pressure, and inspecting for any signs of wear or damage. Rotating tyres regularly can also help ensure even wear.

Brakes

The braking system is another crucial area that often leads to MOT failures. Common issues include worn brake pads, discs, or drums, as well as problems with brake fluid levels or brake lights. During an MOT test, both the efficiency and condition of the braking system are assessed. To avoid brake-related failures, drivers should have their brakes checked regularly by a professional and replace any worn components promptly. Keeping an eye on brake fluid levels and ensuring that the handbrake functions correctly are also important maintenance tasks.

Suspension

Suspension issues are a frequent cause of MOT failures. The suspension system includes components like shock absorbers, springs, and struts, which must be in good working order to pass the MOT. Common problems include worn or broken suspension springs, leaking shock absorbers, and excessive wear in suspension joints or bushings. Regular inspections and maintenance can help identify and address suspension issues before they lead to an MOT failure. Driving over potholes and rough terrain with care can also help prolong the life of the suspension system.

Exhaust and Emissions

Excessive emissions and issues with the exhaust system are common reasons for MOT failure. Vehicles must meet specific emissions standards, which are tested during the MOT. Common problems include leaks or holes in the exhaust system, a malfunctioning catalytic converter, or a failed oxygen sensor. To avoid emissions-related failures, drivers should ensure that their vehicle is regularly serviced and that the exhaust system is inspected for leaks or damage. Using high-quality fuel and additives can also help maintain the efficiency of the catalytic converter and other emissions control components.

Proper exhaust and emissions control is crucial for reducing pollutants and maintaining vehicle efficiency. A well-functioning exhaust system minimizes harmful emissions, ensuring cleaner air and compliance with environmental regulations. Regular maintenance, including checks on the exhaust system, prevents costly repairs and promotes vehicle longevity. In a similar vein, upholstery service, while focusing on restoring the appearance and comfort of furniture, also indirectly contributes to a healthier environment by using eco-friendly materials and techniques that reduce waste and emissions.

Visibility

Visibility issues, particularly with the windscreen and mirrors, often lead to MOT failures. The windscreen must be free from significant damage, such as large chips or cracks, especially in the driver’s line of sight. Windscreen wipers and washers must also be fully operational. Rear-view and side mirrors should be intact and correctly adjusted. To avoid visibility-related failures, drivers should regularly check their windscreen for damage and ensure that wiper blades are in good condition. Replacing damaged or worn wiper blades and keeping the windscreen clean can help maintain optimal visibility.

Registration Plates and VIN

Problems with registration plates and the Vehicle Identification Number (VIN) can also result in MOT failure. Registration plates must be clean, legible, and conform to specific standards regarding font and spacing. The VIN, which uniquely identifies the vehicle, must be clearly visible and not tampered with. To prevent issues with registration plates, drivers should ensure that plates are clean, correctly fitted, and meet legal standards. Checking that the VIN is clearly visible and matches the vehicle’s documentation is also crucial.

Steering

The steering system is another critical area assessed during the MOT test. Common steering-related issues that lead to failure include excessive play in the steering wheel, worn steering components, and leaks in the power steering system. Regular maintenance of the steering system is essential to ensure safe and responsive handling. Drivers should have their steering system checked by a professional if they notice any unusual noises, difficulty steering, or excessive play in the steering wheel. Promptly addressing any identified issues can help prevent MOT failure.

Fuel System

Fuel system problems can also cause a vehicle to fail its MOT. Issues such as fuel leaks, a damaged fuel tank, or problems with the fuel cap can all result in failure. The fuel cap must fit securely and seal properly to prevent fuel leakage and vapour emissions. Regularly inspecting the fuel system for leaks and ensuring that the fuel cap is in good condition can help avoid fuel system-related MOT failures. If any leaks or damage are detected, they should be repaired promptly by a qualified mechanic.

The fuel system is crucial for your vehicle’s performance, delivering the right amount of fuel to the engine. It includes components such as the fuel pump, filter, and injectors, all of which need to be in good working condition. A faulty fuel system can lead to poor engine performance, increased emissions, and potential breakdowns. If your vehicle is experiencing issues like difficulty starting, poor acceleration, or excessive fuel consumption, these could be signs that it might fail the MOT test. Regular maintenance and timely repairs of the fuel system can help ensure your vehicle passes inspection.

Body and Structure

The overall condition of the vehicle’s body and structure is assessed during the MOT test. Significant corrosion, sharp edges, or damage that affects the vehicle’s safety can result in failure. Rust is a common issue, especially in older vehicles, and can weaken the vehicle’s structure. To avoid body and structure-related MOT failures, drivers should regularly inspect their vehicle for signs of rust or damage and address any issues promptly. Keeping the vehicle clean and using rust prevention treatments can also help maintain the integrity of the vehicle’s body and structure.

When considering a vehicle’s body and structure, it’s crucial to ensure both integrity and aesthetics. Regular Maintenance and Overhaul Testing (MOT) checks help detect any structural issues that might compromise safety. A well-maintained body not only enhances the vehicle’s appearance but also contributes to its longevity. For optimal results, professional service from a reputable bodyshop is essential. They offer expert repairs and refinishing that align with MOT standards, ensuring your vehicle remains in peak condition and retains its value. Regular MOT, service and bodyshop service can prevent minor issues from escalating into major problems.

Seat Belts and Seats

Seat belts and seats are essential for passenger safety and are thoroughly checked during the MOT test. Common issues include frayed or damaged seat belts, faulty buckles, or seats that do not securely lock in position. To prevent seat belt and seat-related failures, drivers should regularly inspect seat belts for any signs of wear or damage and ensure that all seat belts and buckles function correctly. Checking that seats are securely fitted and adjusting mechanisms work properly is also important.

Driver’s View of the Road

The driver’s view of the road is crucial for safe driving and is assessed during the MOT test. Obstructions such as stickers, cracks, or chips in the windscreen, or objects hanging from the rear-view mirror can result in failure. To avoid issues related to the driver’s view of the road, drivers should ensure that the windscreen is clear and free from obstructions. Removing any unnecessary items from the windscreen and ensuring that the area within the driver’s line of sight is clean and free from damage can help pass the MOT test.

Electrical Equipment

Electrical equipment, including the horn, battery, and wiring, is also checked during the MOT test. Common issues include a faulty horn, a weak or discharged battery, and damaged or exposed wiring. Ensuring that the horn is operational, the battery is in good condition, and all wiring is secure and undamaged can help prevent electrical equipment-related MOT failures. Regular vehicle servicing can help identify and address any potential electrical issues before they become a problem during the MOT test.

Electrical equipment in vehicles encompasses components like the battery, alternator, and wiring, crucial for the proper functioning of a car’s electrical system. Proper maintenance of these components is essential to prevent issues during a vehicle’s MOT (Ministry of Transport) test. Common reasons for MOT failure related to electrical equipment include faulty lights, malfunctioning indicators, and battery problems. Ensuring that all electrical systems are in good working order can help avoid these failures and ensure a smoother MOT process. Regular checks and timely repairs of electrical equipment are vital for passing the test.

FAQs

What is the most common fail on a MOT?

Blown bulbs are the single biggest cause of failures, and are one of the simplest and cheapest to fix.

What causes MOT failure?

The three most common reasons for MOT failures are faults with lights, suspension and brakes. We’ve got a full article all about the most common MOT fails and how to avoid them too.

What makes a tyre fail an MOT?

Tyres with tread depth lower than 1.6mm is illegal and will result in an MOT fail.

What is the main purpose of MOT?

In chemistry, molecular orbital theory (MO theory or MOT) is a method for describing the electronic structure of molecules using quantum mechanics. It was proposed early in the 20th century.

What is the principle of MOT?

Principles of Molecular Orbital Theory. In molecules, atomic orbitals combine to form molecular orbitals which surround the molecule. Similar to atomic orbitals, molecular orbitals are wave functions giving the probability of finding an electron in certain regions of a molecule.

Conclusion

MOT failures are often caused by common and preventable issues. Regular maintenance and inspections can help identify and address potential problems before the MOT test. By paying attention to the condition of lighting and signalling, tyres and wheels, brakes, suspension, exhaust and emissions, visibility, registration plates and VIN, steering, fuel system, body and structure, seat belts and seats, the driver’s view of the road, and electrical equipment, drivers can significantly increase their chances of passing the MOT test. Keeping a vehicle in good condition not only helps pass the MOT but also ensures safer and more reliable transportation.