What are the most common reasons for vehicle MOT failure?

Have you ever dreaded the thought of your car failing its MOT test? You’re not alone! The MOT test, a yearly check-up for vehicles in the UK, ensures they meet essential safety and environmental standards. Despite regular maintenance, many cars still stumble over common pitfalls during this inspection. From faulty brakes to worn-out tyres and dimming lights, the reasons behind MOT failures are often preventable with a bit of forethought. In this blog post, Car & Bike Magic dives to the most common culprits that could turn your MOT test into a frustrating experience, and learn how to keep your vehicle in top shape.

Brakes and Braking System

One of the most common reasons for MOT failure is issues with the braking system. The brakes are arguably the most crucial component of a vehicle, directly affecting safety. The MOT test checks for various aspects of the braking system, including brake pads, discs, and the brake fluid level. Common problems include worn brake pads and discs, which can significantly reduce braking efficiency. Additionally, leaks in the brake fluid system can cause a loss of hydraulic pressure, leading to brake failure. Regular maintenance and timely replacement of worn components are essential to ensure the braking system functions correctly.

Lighting and Signalling Equipment

Faulty lighting and signalling equipment are also frequent causes of MOT failure. The test inspects all external lights, including headlights, taillights, brake lights, indicators, and fog lights, to ensure they are functioning correctly. Common issues include blown bulbs, faulty connections, and misaligned headlights. These problems not only cause an MOT failure but also pose significant safety risks, especially during night driving or adverse weather conditions. Ensuring all lights are in working order and replacing any defective bulbs or components can prevent these issues.

Lighting and signaling equipment are vital for road safety, ensuring visibility and communication between drivers. Regular maintenance and inspection of these components are crucial to ensure they function correctly. MOT tests often include checks on lighting and signaling systems to ensure compliance with safety regulations. Service centers offer maintenance and repair services for faulty lights and signals. Additionally, body shops may also address issues related to damaged lighting and signaling equipment during vehicle repairs.

Tyres and Wheels

Tyres and wheels are critical for vehicle safety and are another common reason for MOT failures. The test examines the tyre tread depth, which must be at least 1.6mm across the central three-quarters of the tyre. Tyres must also be free from significant cuts, bulges, or other damage. Incorrect tyre pressure and wheel alignment can also lead to failure, as they affect the vehicle’s handling and stability. Regularly checking tyre condition and pressure, and ensuring proper wheel alignment, can help prevent MOT failures related to tyres and wheels.

Suspension System

The suspension system, which includes shock absorbers, springs, and other components, is vital for a smooth and stable ride. The MOT test assesses the suspension’s condition and performance, looking for issues such as broken or worn-out components, leaks in shock absorbers, and excessive play in the suspension arms. Common signs of suspension problems include uneven tyre wear, a bouncy ride, and unusual noises when driving over bumps. Regular inspection and maintenance of the suspension system can help identify and rectify issues before the MOT test.

Steering System

The steering system’s integrity is crucial for vehicle control and safety, making it a key focus of the MOT test. The test checks for excessive play, stiffness, or unusual noises in the steering mechanism, which can indicate worn or damaged components such as the steering rack, power steering pump, or steering column. Any leaks in the power steering fluid system are also scrutinized. Regular checks and maintenance of the steering system can help ensure it remains in good working order, preventing MOT failures and enhancing driving safety.

The steering system is a critical component of any vehicle, responsible for controlling direction and maneuverability. Regular maintenance and inspection are essential to ensure smooth operation and driver safety. During interior detailing services, attention to the steering wheel and column enhances the overall aesthetics and comfort of the vehicle’s interior. Detailing may involve cleaning, conditioning, and restoring these components, ensuring they not only look great but also function optimally, contributing to a satisfying driving experience.

Exhaust and Emissions

With increasing concerns about environmental pollution, the exhaust system and emissions are significant areas of focus in the MOT test. The test measures the levels of various pollutants, including carbon monoxide, hydrocarbons, and nitrogen oxides, to ensure they are within permissible limits. A faulty exhaust system, such as leaks or a malfunctioning catalytic converter, can cause emissions to exceed legal limits. Additionally, issues with the engine’s fuel and ignition systems can lead to increased emissions. Regular servicing and timely repairs of the exhaust and emission control systems can help keep emissions within acceptable levels.

Bodywork and Structure

The vehicle’s bodywork and structure are examined during the MOT test to ensure there are no excessive corrosion, damage, or other structural weaknesses that could compromise safety. The test looks for rust in critical areas such as the chassis, sills, and suspension mounting points. Any significant damage or deterioration in these areas can result in an MOT failure. Regular inspection and repair of any rust or damage, and taking preventative measures such as rust-proofing, can help maintain the structural integrity of the vehicle.

Seatbelts and Restraints

Seatbelts and other restraint systems are crucial for occupant safety and are rigorously checked during the MOT test. The test ensures that all seatbelts are present, correctly fitted, and in good working order. Common issues include frayed or damaged belts, faulty locking mechanisms, and missing seatbelt anchorages. Ensuring that all seatbelts and restraint systems are regularly inspected and maintained can help prevent MOT failures and enhance passenger safety.

Windscreen, Wipers, and Washer Fluid

Clear visibility is essential for safe driving, making the condition of the windscreen, wipers, and washer fluid system critical components of the MOT test. The test checks for cracks or chips in the windscreen, especially in the driver’s line of sight, as well as the effectiveness of the wipers and the presence of sufficient washer fluid. Common issues include worn or damaged wiper blades, blocked washer jets, and significant windscreen damage. Regular maintenance of these components, including replacing wiper blades and keeping the washer fluid reservoir filled, can help ensure clear visibility and prevent MOT failures.

Number Plates and VIN

The MOT test includes checks on the vehicle’s number plates and Vehicle Identification Number (VIN) to ensure they are clearly visible and comply with legal requirements. Common issues that can lead to MOT failures include incorrect number plate fonts, damage or excessive wear that makes the number plate illegible, and missing or unreadable VIN plates. Ensuring that number plates are clean, undamaged, and compliant with regulations, and that the VIN plate is clearly visible, can help avoid failures in this area.

Number plates and Vehicle Identification Numbers (VINs) are crucial for vehicle identification and registration. Number plates display unique identification codes assigned to vehicles, while VINs provide detailed information about a vehicle’s make, model, and manufacturing specifications. When considering matching original upholstery color, VINs can be useful in determining the vehicle’s original specifications, aiding in sourcing appropriate materials for restoration. Utilizing VIN information can increase the likelihood of achieving an accurate match for the vehicle’s original upholstery color during restoration processes.

Fuel System

The fuel system is another critical component examined during the MOT test. The test looks for any leaks in the fuel system, the condition of the fuel cap, and the secure mounting of fuel lines. Leaks in the fuel system can pose serious safety hazards, increasing the risk of fire. Additionally, a faulty or missing fuel cap can lead to fuel evaporation and increased emissions. Regular inspection and maintenance of the fuel system, including checking for leaks and ensuring the fuel cap is in good condition, can help prevent MOT failures.


The condition and positioning of the vehicle’s mirrors are crucial for safe driving and are checked during the MOT test. The test ensures that the rear-view and side mirrors are securely attached, in good condition, and provide an adequate field of view. Common issues include cracked or broken mirrors, loose mountings, and incorrect positioning. Regularly inspecting and maintaining the mirrors can help ensure they provide the necessary visibility for safe driving and prevent MOT failures.

Electrical Components

The vehicle’s electrical components, including the battery, wiring, and electrical connections, are also examined during the MOT test. Common issues include loose or corroded battery terminals, damaged wiring, and faulty electrical connections. These problems can lead to various issues, including difficulties starting the vehicle and malfunctioning lights or indicators. Regular inspection and maintenance of the vehicle’s electrical system can help identify and rectify issues before they lead to an MOT failure.

Electrical components in vehicles encompass a wide array of systems, including wiring, fuses, batteries, and electronic control units. Ensuring their proper functioning is crucial for overall vehicle performance and safety. When selecting an MOT service provider in Sunderland, it’s essential to find one with expertise in diagnosing and repairing electrical issues. Look for providers equipped with modern diagnostic tools and experienced technicians capable of accurately assessing and resolving electrical problems to ensure a thorough and reliable MOT inspection.


What is a major defect on MOT?

If a major fault is identified, the vehicle will fail the MOT test, but the driver is allowed to take the vehicle to a different garage for repairs. Examples of major faults found during an MOT could include ‘a headlamp is likely to become detached’ or ‘brake fluid is significantly below minimum mark’.

What warrants an MOT failure?

Lamps, reflectors, and electrical equipment – The most common MOT failure class, accounting for 27% of all defects, included lamps, reflectors, and electrical equipment.

What happens if MOT fails?

What happens if I fail my MOT? If your car fails its MOT, you’ll be issued a VT30 Refusal of an MOT Test Certificate. The certificate will explain the reason (or reasons) why your car failed its test. A VT30 means your car isn’t safe to drive on the roads and you’ll need to get it fixed before you drive it again.

What will make an MOT fail?

Around 1.5 million vehicles fail their MOT due to simple things such as faulty bulbs, too little tyre tread, or even empty windscreen washer fluid bottles. It’s possible to anticipate most of these issues with a quick check of your car.

How long does an MOT normally last?

An MOT lasts for a year. To find out when it runs out you can either: check your MOT history online. check the date that’s printed on your current MOT certificate, if you have one.


Understanding the common reasons for MOT failures can save you time, money, and hassle. Issues like faulty brakes, worn tyres, and malfunctioning lights are often preventable with regular maintenance and timely repairs. Paying attention to the suspension, steering, exhaust system, and other critical components ensures your vehicle remains safe and compliant with regulations. By staying proactive and addressing these common problems, you can significantly reduce the risk of failing your MOT test. Ultimately, a well-maintained vehicle not only passes the MOT with flying colors but also contributes to safer roads and a cleaner environment for everyone.

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