MOT Faults Explained

The MOT test is a crucial annual check for vehicles over three years old in the UK, designed to ensure roadworthiness and safety. While many drivers are familiar with the concept, understanding precisely what constitutes a 'dangerous' MOT fault can be a source of confusion. A dangerous fault is the most serious category of defect identified during an MOT test, indicating an immediate and significant risk to road safety, or a severe environmental impact. If your vehicle is identified as having a dangerous fault, it must not be driven on public roads until it has been repaired and retested.

What Makes an MOT Fault 'Dangerous'?

The Driver and Vehicle Standards Agency (DVSA) categorises MOT failures into three main types: Advisory, Major, and Dangerous. A dangerous fault is one that poses a direct and immediate risk. This isn't just about minor wear and tear; it's about components that, if they fail, could cause a catastrophic loss of control, a severe accident, or significant harm to others. Think of it as anything that makes your car, in its current state, a significant hazard on the road.

Common Areas for Dangerous MOT Faults

Several key areas of a vehicle are scrutinised during an MOT, and faults in these areas are more likely to be classified as dangerous:

1. Braking System Failures

The braking system is paramount for safety. Any issue that compromises the vehicle's ability to stop effectively will be a major concern. Dangerous faults in this area include:

• Severely worn or damaged brake discs or pads: If the friction material is almost entirely gone, or the discs are so corroded they are at risk of breaking apart, this is dangerous.
• Leaking brake fluid: A loss of brake fluid means a loss of braking power. Any visible leak, especially from the brake lines or master cylinder, is a serious issue.
• Malfunctioning anti-lock braking system (ABS) warning light: If the ABS warning light remains illuminated, it suggests a fault with the system, which could impact braking performance in certain conditions.
• Severely corroded or damaged brake pipes or hoses: If these are so corroded or damaged that they are likely to fail under pressure, it's a dangerous fault.
• Inoperative parking brake: If the handbrake or electronic parking brake doesn't hold the vehicle on a test ramp, it's a dangerous fault.

2. Steering and Suspension

Proper steering and a stable suspension are vital for maintaining control. Dangerous faults here can include:

• Severely worn or damaged steering components: This could include worn track rod ends, ball joints, or steering rack issues that result in excessive play or the risk of them separating.
• Damaged or corroded suspension components: Fractured springs, severely corroded suspension arms, or damaged shock absorbers that are leaking significantly or are completely ineffective can be dangerous.
• Loose or insecure steering column or shaft: Any play or looseness here compromises the driver's ability to control the direction of the vehicle.

3. Tyres and Wheels

The tyres are the only point of contact between your car and the road. Their condition is critical.

• Tyres with severe damage or under-inflation: Tyres with cuts, bulges, or exposed ply/cord are dangerous. Similarly, tyres that are significantly under-inflated and can't be properly inflated are also a failure.
• Tyres with tread depth below the legal limit (1.6mm): While this is a major fault, if the tread is so worn that the tyre is visibly falling apart or has exposed cords, it can be deemed dangerous.
• Wheels that are cracked or severely damaged: A damaged wheel could lead to a loss of tyre pressure or even wheel failure.
• Loose wheel nuts: If wheel nuts are missing or loose, the wheel can detach from the vehicle, which is extremely dangerous.

4. Lights and Visibility

While most lighting faults are advisory or major, some can be dangerous.

• Headlights that are misaligned or not working: If headlights are aimed so high or low that they significantly impair visibility or dazzle other drivers, this can be dangerous. Non-functioning headlights, especially at night, are also a major hazard.
• Obstructions to the driver's field of vision: This includes anything that severely restricts the driver's view, such as large cracks in the windscreen directly in the driver's line of sight, or items obscuring the windscreen.

5. Exhaust and Emissions

While emissions failures are typically about meeting standards, some exhaust issues can be dangerous.

• Severely corroded or damaged exhaust system: If the exhaust is so corroded that it's likely to break apart or detach, or if there are holes that could allow exhaust fumes into the cabin, this is a dangerous fault.

6. Structure and Body

The structural integrity of the vehicle is vital for occupant safety.

• Significant corrosion in structural areas: This includes areas like the chassis, suspension mounting points, and seat belt mountings. Excessive rust that compromises the strength of these components is a dangerous fault.
• Sharp or protruding objects: Any sharp edges or protruding parts that could cause injury to pedestrians or other road users are considered dangerous.

What Happens If Your Car Fails with a Dangerous Fault?

As mentioned, if your vehicle is issued a 'dangerous' failure notice, you are legally prohibited from driving it on public roads. This means you cannot drive it home, even if it's a short distance. The only exceptions are:

• Driving to a pre-arranged MOT test appointment.
• Driving to a place of repair.

In both these scenarios, you must ensure the vehicle is in a condition where it is safe to drive those short distances. If you are caught driving a vehicle with a dangerous fault (and not under one of these exceptions), you can face prosecution, fines, and penalty points on your licence. The vehicle itself could also be impounded.

What to Do After a Dangerous Fault

The immediate action required is to get the vehicle repaired. You will need to take it to a qualified mechanic. Once the repairs are completed, the vehicle will need to undergo a partial or full retest, depending on the nature of the faults and the repairs carried out. A partial retest usually covers only the items that failed, while a full retest may be required if the vehicle has been off the road for an extended period or if the initial MOT has expired.

Preventing Dangerous MOT Faults

The best way to avoid a dangerous MOT fault is through regular vehicle maintenance. Don't wait for the MOT to find problems. Keep an eye on:

• Brake fluid levels and pad wear: Have these checked regularly, especially if you notice any changes in braking performance.
• Tyre condition and pressure: Visually inspect your tyres weekly for wear, damage, and correct inflation.
• Lights: Regularly check that all your lights are working correctly.
• Steering and suspension: Listen for unusual noises when turning or going over bumps, and be aware of any changes in how the car handles.
• General corrosion: While hard to spot all areas, be mindful of any significant rust appearing on the bodywork or undercarriage.

By being proactive with your car's upkeep, you not only increase its lifespan but also ensure its safety for yourself, your passengers, and other road users. An MOT is a snapshot of your car's condition on a particular day, but consistent maintenance is key to long-term roadworthiness.

Frequently Asked Questions

Q1: Can a car fail its MOT for something minor?
Yes, minor issues can result in an 'advisory' notice, which suggests improvements are needed but doesn't cause an immediate failure. However, a combination of advisories can sometimes lead to a major or dangerous fault if they worsen.

Q2: What is the difference between a 'major' and a 'dangerous' fault?
A 'major' fault means the vehicle fails the MOT and needs to be repaired. It indicates a problem that could affect safety, performance, or emissions, but it's not an immediate, severe risk. A 'dangerous' fault is more severe, posing an immediate and significant risk to road safety, meaning the vehicle cannot be legally driven.

Q3: If my car fails with a dangerous fault, can I drive it to a repair shop?
Only if the MOT has not yet expired and you are driving directly to a place of repair or a pre-booked MOT retest. If the MOT has expired, you cannot drive it at all, except to a pre-booked retest.

Q4: How long do I have to get repairs done after failing an MOT?
There's no strict time limit to complete repairs, but you cannot legally drive the vehicle on public roads until it has been repaired and passes a retest (unless you are driving it to a repairer or retest as described above). The original MOT certificate becomes invalid if it fails with a dangerous fault.

Q5: What if the MOT tester missed a dangerous fault?
While MOT testers are trained professionals, mistakes can happen. If you discover a dangerous fault after passing your MOT, you should contact the garage that performed the test. The DVSA also has a procedure for reporting concerns about MOT testing stations.

Understanding these potential MOT faults, especially the dangerous ones, empowers you to keep your vehicle in top condition and ensure it remains safe and legal on the road. Regular checks and proactive maintenance are your best allies.