Common MOT Failures & How to Avoid Them

The annual MOT test is a crucial requirement for all vehicles in the UK, ensuring they meet safety and environmental standards. However, a significant number of cars, approximately one-third, fail their initial MOT inspection. This can lead to unexpected costs, inconvenience, and the worry of having a non-roadworthy vehicle. At Carlingo Harrogate, we've compiled a comprehensive guide to the most common MOT failures, offering practical advice to help you keep your vehicle in top condition and maximise your chances of passing first time.

Understanding the Most Common MOT Pitfalls

Failing an MOT can be a stressful experience, but by understanding the typical reasons for failure, you can take proactive steps to prevent them. Let's delve into the most frequent culprits:

1. Lighting and Signalling (Approx. 30% of Failures)

Faulty lights are the leading cause of MOT failures, highlighting the importance of visibility and signalling for road safety. Issues can range from simple blown bulbs to more complex electrical faults.

• Blown Bulbs: Headlights, brake lights, and indicator bulbs are checked for functionality. A single blown bulb can lead to a fail.
• Misaligned Headlights: Headlights that are too high or too low can dazzle other drivers or fail to illuminate the road adequately.
• Cracked Light Covers: Damaged covers can affect the light's projection and may allow moisture to enter, causing further issues.
• Faulty Electrical Connections: Corroded or loose wiring can cause intermittent or complete failure of lighting systems.

Prevention Tips:

• Regular Checks: Periodically walk around your vehicle with the lights on to ensure all are functioning correctly. Ask a friend or family member to help check brake lights.
• Prompt Replacements: Replace any blown bulbs as soon as you notice them. Keeping spare bulbs in your glove compartment can be a lifesaver.
• Cleanliness: Regularly clean your light covers to ensure maximum light output and visibility.

2. Suspension and Steering (Approx. 20% of Failures)

Problems with your suspension and steering systems compromise your vehicle's handling and safety. These components are critical for maintaining control, especially during braking and cornering.

• Worn Shock Absorbers: Deteriorated shock absorbers lead to poor ride quality and reduced tyre contact with the road.
• Damaged Suspension Springs: Fractured or sagging springs can affect ride height and handling.
• Loose Steering Components: Wear and tear can lead to looseness in components like track rod ends, affecting steering precision.
• Excessive Play in Steering Wheel: A steering wheel that feels loose or has too much free movement indicates wear in the steering system.
• Ball Joint Issues: Worn ball joints are a critical safety failure, as they connect suspension components and can lead to loss of steering control.

Prevention Tips:

• Listen for Noises: Pay attention to knocking or clunking sounds when driving over bumps or uneven surfaces.
• Observe Vehicle Behaviour: If your car bounces excessively after hitting a bump, your shock absorbers may be worn.
• Tyre Wear: Uneven tyre wear, particularly on the edges, can be a strong indicator of suspension alignment problems.
• Steering Feel: Notice if your car pulls to one side or if you feel vibrations through the steering wheel.
• Professional Inspection: Consider having your suspension and steering system inspected annually, especially if you drive on poor road surfaces frequently.

3. Brakes (Approx. 17% of Failures)

The braking system is paramount for safety. Any issues here can have severe consequences, making it a high-priority check during an MOT.

• Worn Brake Pads or Discs: Reduced braking performance and potential damage to other braking components.
• Uneven Braking: If the braking force is not distributed evenly between the wheels, it can cause the vehicle to pull to one side.
• Brake Fluid Leaks: Low brake fluid levels can lead to a spongy pedal and reduced braking efficiency.
• Imbalanced Braking Forces: A failure in one part of the braking system can lead to significant imbalances.
• Handbrake Ineffectiveness: A handbrake that doesn't hold the vehicle securely on a gradient is a critical failure.

Prevention Tips:

• Listen for Sounds: Grinding or high-pitched squealing noises when braking often indicate worn pads.
• Regular Checks: Have your brake pads and discs inspected regularly, typically every 12,000 miles or as per your manufacturer's service schedule.
• Pedal Feel: A spongy brake pedal or one that sinks to the floor requires immediate professional attention.
• Fluid Levels: Ensure your brake fluid is at the correct level and changed according to the manufacturer's recommendations.
• Handbrake Test: Periodically test your handbrake on a slight incline to ensure it functions effectively.

4. Tyres and Wheels (Approx. 10% of Failures)

Proper tyres are essential for grip, braking, and overall vehicle stability. The legal minimum tread depth in the UK is 1.6mm across the central three-quarters of the tyre's breadth.

• Insufficient Tread Depth: Illegal tread depth significantly reduces grip, especially in wet conditions.
• Uneven Wear Patterns: This can indicate issues with wheel alignment, tyre pressure, or suspension.
• Bulges or Cuts in Sidewalls: Damage to the tyre sidewall can lead to a sudden blowout.
• Incorrect Tyre Size: Using tyres that are not the correct size or specification for your vehicle.
• Mismatched Tyres: Tyres with different tread patterns or wear levels on the same axle.

Prevention Tips:

• Tyre Pressure: Check your tyre pressures monthly and before any long journeys. Always use the recommended pressures found in your vehicle's handbook or on a sticker in the doorjamb.
• Tread Depth Check: Use the 20p coin test: insert a 20p coin into the tread groove. If the outer band of the coin is visible, the tread is likely below the legal limit.
• Tyre Rotation: Rotate your tyres according to your manufacturer's recommendations to ensure even wear.
• Visual Inspection: Regularly inspect your tyres for any embedded objects, cuts, or bulges.
• Wheel Alignment: If you notice uneven tyre wear, have your wheel alignment checked.

5. Visibility Issues (Approx. 8% of Failures)

Clear visibility is crucial for safe driving. Anything that obstructs the driver's view or impairs their ability to see and be seen can lead to an MOT failure.

• Damaged Windscreen: Cracks or chips in the windscreen, particularly within the driver's primary field of vision, are not permitted.
• Faulty Wipers: Wipers that leave streaks or don't clear the screen effectively.
• Empty or Ineffective Screen Wash: The screen wash system must be functional to clear the windscreen.
• Damaged or Missing Mirrors: All mirrors must be present, secure, and in good condition.
• Obstructions: Items like air fresheners, sat-navs, or even excessive stickers can be a fail if they obstruct the driver's view.

Prevention Tips:

• Windscreen Chips: Get small chips repaired promptly; they can spread into larger cracks due to temperature changes or vibrations.
• Wiper Blades: Replace wiper blades every 6-12 months, or when they start to streak or judder.
• Screen Wash: Keep your screen wash reservoir topped up with a proper screen wash solution, especially during colder months.
• Mirror Check: Ensure all your mirrors are securely fitted and correctly adjusted.
• Clear View: Keep your windscreen and windows clean and free from any obstructions.

6. Exhaust and Emissions (Approx. 7% of Failures)

With increasingly stringent environmental regulations, emissions tests are a significant part of the MOT. A well-maintained engine and exhaust system are key.

• Excessive Emissions: High levels of pollutants like carbon monoxide and hydrocarbons indicate engine running issues.
• Damaged Exhaust System: Leaks, corrosion, or structural damage to the exhaust can cause failures.
• DPF Issues: For diesel vehicles, a blocked or faulty Diesel Particulate Filter (DPF) can lead to emission failures.
• Exhaust Leaks: Can affect emissions readings and create noise pollution.
• Emissions Warning Lights: Lights like the 'Check Engine' light, often linked to emissions systems, will cause a fail if illuminated.

Prevention Tips:

• Regular Servicing: A well-serviced engine runs more efficiently and produces fewer emissions.
• Quality Fuel: Using good quality fuel from reputable suppliers can help maintain engine health.
• Address Warning Lights: Never ignore dashboard warning lights; get them diagnosed and fixed promptly.
• DPF Regeneration: If you have a diesel with a DPF, ensure you take regular longer journeys at consistent speeds to allow the filter to regenerate.
• Exhaust Noise: Listen for any changes in exhaust noise, which could indicate a leak.

7. Body, Structure, and General Items (Approx. 6% of Failures)

While seemingly less critical than mechanical components, structural integrity and general safety features are thoroughly checked.

• Excessive Corrosion: Significant rust, especially on structural components or load-bearing areas, is a major fail.
• Damaged or Loose Bumpers: Bumpers must be securely attached and free from sharp edges.
• Sharp Edges: Any sharp protrusions on the bodywork that could injure pedestrians or occupants.
• Insecure Seats or Seatbelts: Seats must be firmly fixed, and seatbelts must be in good condition and securely anchored.
• Bonnet/Boot Latch: The bonnet and boot must close securely and be able to be opened from the outside.

Prevention Tips:

• Wash Your Car: Regular washing, especially in winter to remove salt, can prevent corrosion.
• Address Rust: Treat minor rust spots as soon as they appear to prevent them from spreading.
• Check Closures: Ensure all doors, the bonnet, and the boot latch securely.
• Seatbelt Inspection: Check seatbelts for any fraying or damage and ensure they retract correctly.
• Repair Bodywork: Fix any damage to the bodywork promptly.

8. Fuel and Electrical Systems (Approx. 5% of Failures)

Issues with the fuel delivery system or the vehicle's electrical components can also lead to MOT failure.

• Fuel Leaks: Any sign of fuel leaks is a critical safety failure.
• Insecure Fuel Cap: The fuel cap must seal properly to prevent evaporative emissions escaping.
• Battery Security: The battery must be securely mounted and not corroded.
• Electrical Wiring Issues: Exposed, damaged, or incorrectly routed wiring can be a fail.
• Dashboard Warning Lights: As mentioned, illuminated warning lights related to critical systems will cause a fail.

Prevention Tips:

• Leak Checks: Occasionally look under your car for any signs of fluid leaks.
• Fuel Cap: Ensure your fuel cap clicks shut when tightened, indicating a secure seal.
• Battery Mount: Check that your battery is firmly secured in its bracket.
• Professional Diagnosis: If you see any warning lights, seek professional diagnosis rather than attempting DIY fixes, especially for electrical issues.

Proactive Maintenance with Carlingo Harrogate

We understand that keeping a vehicle in perfect condition can seem daunting. That's why Carlingo Harrogate offers pre-MOT inspections. Our experienced technicians can thoroughly check your vehicle for potential issues before your official MOT test. This proactive approach can save you considerable time, money, and the stress of an unexpected failure.

Remember, consistent regular maintenance throughout the year is far more effective than trying to rectify issues at the last minute. Many common MOT failures can be easily avoided with routine care and attention.

If you have any concerns about your vehicle's condition or need advice on preparing for your MOT, our friendly team at Carlingo Harrogate is always on hand to provide expert guidance tailored to your specific vehicle. By addressing minor issues before they escalate, you can ensure your car remains safe, legal, and reliable on the road.

Visit Carlingo Harrogate today for comprehensive vehicle checks and expert advice to keep your car in prime condition year-round.

Frequently Asked Questions (FAQs)

Q1: What is the most common reason for an MOT failure?
The most common reason for an MOT failure is faulty lighting and signalling, accounting for around 30% of all failures.

Q2: Can I check my car's MOT history?
Yes, you can check a vehicle's MOT history online via the UK government's official website using its registration number.

Q3: What happens if my car fails its MOT?
If your car fails its MOT, it is illegal to drive it on the road unless it is being driven to a pre-booked MOT test appointment or to a place of repair. You will receive a 'refusal of an MOT test certificate' document detailing the reasons for failure.

Q4: How much tread depth is legally required on a tyre?
The legal minimum tread depth for car tyres in the UK is 1.6mm across the central three-quarters of the tyre's width.

Q5: Is it worth getting a pre-MOT check?
Absolutely. A pre-MOT check can identify potential issues before the official test, saving you the cost and inconvenience of a re-test and ensuring your vehicle is safe.