Getting your vehicle ready for an MOT can be nerve-wracking, especially if you're unsure what the test will focus on. However, understanding the most common MOT failure reasons can make the process much less stressful. From lighting issues to brake performance, this article will highlight the top 10 reasons cars fail their MOTs—and, importantly, what you can do to avoid them. Taking some time to do a pre-MOT inspection can help prevent surprises, save money, and keep your vehicle roadworthy.
1. Lights and Signaling Problems
Lighting and signaling issues are the number one reason cars fail MOTs. This includes faulty or dim headlights, brake lights, and indicators, as well as rear registration plate lights.
How to Avoid: Check all lights before the MOT. Turn on your headlights, indicators, and brake lights, and ensure they’re all working well. Inspect for dimming or flickering lights, as these could indicate a need for replacement. Keeping spare bulbs handy is also a good idea.
2. Brakes and Brake Performance
Brakes are critical for vehicle safety, and even minor issues with braking can lead to an MOT failure. Common problems include worn brake pads, uneven braking, or malfunctioning handbrakes.
How to Avoid: Get your brakes inspected regularly. Listen for any grinding or squealing noises, which are signs that brake pads might be wearing down. Also, check the handbrake’s tension, as an overly loose handbrake can result in failure. Regular brake checks are an investment in both safety and passing your MOT.
3. Tyre Condition and Tread Depth
Tyres with low tread depth or visible damage are a common reason for MOT failures. The UK legal minimum tread depth is 1.6mm, but tyres nearing that depth should be changed for both safety and test readiness.
How to Avoid: Measure your tyre tread depth regularly, especially before an MOT. Most modern tyres have tread wear indicators to make this easier. Additionally, inspect tyres for bulges, cuts, or signs of wear, as these are often causes for failure.
4. Suspension Issues
Faulty suspension components, like worn-out shock absorbers or broken springs, are frequently found in MOT failures. Suspension affects vehicle control and stability, so it’s a major focus during testing.
How to Avoid: Suspension problems can be hard to detect without a professional check, but watch for signs like uneven tyre wear or a bumpy, uncomfortable ride. If your vehicle tends to bounce excessively after hitting a bump, get the suspension checked before the MOT.
5. Excessive Exhaust Emissions
High emissions are a top reason for failure, especially for older cars. MOT tests now include stricter emission standards, particularly for diesel vehicles.
How to Avoid: Consider a pre-MOT emissions test if you drive an older or high-mileage vehicle. Regular maintenance, like changing the air filter and keeping the fuel system clean, can improve emissions. For diesel cars, a thorough drive before the test can help clear out soot build-up.
6. Steering Components
Issues with the steering system, such as worn steering rack joints or loose components, are other common MOT failures. These can affect control and stability, making them a major safety concern.
How to Avoid: Have your steering checked by a professional if you notice any unusual sounds or stiffness. Keeping fluid levels topped up and getting steering components inspected as part of routine maintenance will also help.
7. Faulty Mirrors and Windscreen Condition
Cracks or significant chips in the windscreen and issues with mirrors are frequent reasons for MOT failures. Visibility is crucial for safe driving, and testers will look for any obstruction within the driver’s field of view.
How to Avoid: Repair or replace any damaged mirrors and fix chips or cracks in the windscreen before the MOT. Most minor chips can be repaired easily, but larger cracks will require a full replacement.
8. Worn-Out Wipers and Washer Fluid
While it may seem minor, defective wipers or an empty washer reservoir can lead to a failed MOT. These components are essential for clear visibility in adverse weather.
How to Avoid: Check your wipers for any signs of wear and make sure the washer fluid is topped up before the MOT. Replace worn wipers and test the washers to ensure they work correctly.
9. Seat Belt Condition and Functionality
MOT tests include checking all seat belts for wear, damage, and proper functionality. A damaged or non-functioning seat belt is a serious safety issue.
How to Avoid: Inspect all seat belts for signs of fraying or damage, and test their locking mechanisms. Any seat belt that doesn't retract or secure properly should be repaired or replaced before the MOT.
10. Registration Plate Issues
Registration plates that are dirty, cracked, or don’t meet legal standards are another reason for failure. Plates must be clean, legible, and conform to UK regulations.
How to Avoid: Clean your registration plates before the test, and check for any cracks or damage. If your plates are worn or use an illegal font, replace them with standard plates that meet UK regulations.
Final Tips for a Successful MOT
A little preparation can go a long way in ensuring a successful MOT test. Here are some quick pre-MOT inspection tips:
Test drive your car and listen for any unusual sounds.
Check fluid levels for oil, coolant, and brake fluid, as low levels can indicate leaks or system issues.
Get a professional service or pre-MOT check if you’re concerned about specific issues.
Passing the MOT isn’t just about compliance—it’s about keeping your car safe and in top condition. Regular maintenance and a thorough pre-MOT inspection will not only help you avoid unexpected failures but also extend the life of your vehicle.
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