According to the DVSA, around 36 percent of cars fail their MOT on the first attempt. That is more than one in three vehicles. The frustrating thing is that many of these failures are for simple, inexpensive issues that could have been spotted and fixed before the test.
We have been running MOTs at AVS Bransgore for over 25 years, and we see the same problems come up week after week. Here are the top 10 reasons cars fail — and what you can do about each one.
1. Lighting and Signalling (18% of Failures)
This is the single biggest reason for MOT failure, and it is often the cheapest to fix. A blown headlight bulb, a dead indicator, or a faulty number plate light will all result in a fail. Before your MOT, get someone to walk around the car while you operate every light — headlights on dipped and main beam, indicators, brake lights, fog lights, reversing lights, and number plate lights. Most bulbs cost under five pounds and take minutes to replace.
2. Suspension (13% of Failures)
Worn shock absorbers, broken springs, and perished bushes are all common suspension failures. If your car bounces excessively over bumps, leans heavily in corners, or makes clunking noises over rough roads, your suspension probably needs attention. Unfortunately, suspension issues are harder to spot at home — if in doubt, ask us to check it before your MOT.
3. Brakes (10% of Failures)
Worn brake pads, scored discs, and seized calipers are all MOT failures. Listen for any squealing or grinding when you brake, and pay attention to whether the car pulls to one side. Also check your handbrake holds the car on a hill. If you have any doubts about your brakes, get them inspected — brakes are not something to gamble with.
4. Tyres (8% of Failures)
The legal minimum tread depth is 1.6mm across the central three-quarters of the tyre. Use the 20p coin test — if you can see the outer band, your tread is too low. Also check for cuts, bulges, or cracks in the sidewalls, and make sure all four tyres are the correct size and type for your vehicle.
5. Driver's View of the Road (7% of Failures)
Windscreen chips and cracks are a common fail. Any damage larger than 10mm in the driver's direct line of sight (a 290mm zone centred on the steering wheel) will fail. In the rest of the swept area, the limit is 40mm. Also make sure your wipers clear the screen effectively and your washers spray properly.
6. Exhaust Emissions (6% of Failures)
If your engine management light is on, your car will almost certainly fail the emissions test. Diesel cars are tested more strictly, and a clogged DPF is a very common fail. If your diesel has been doing lots of short journeys, take it for a good 20-minute motorway run before the test to help the DPF regenerate.
7. Number Plates (3% of Failures)
Your number plates must be clean, legible, and correctly formatted. No fancy spacing, no bolt heads covering characters, and the plates must not be faded, cracked, or discoloured. This is a surprisingly common and entirely avoidable fail.
8. Seatbelts (3% of Failures)
Check that all seatbelts pull out smoothly, retract properly, and the buckles click in and release cleanly. Look for any fraying, cuts, or damage to the webbing. A seatbelt that does not lock when you tug it sharply will fail.
9. Steering and Wheel Bearings (2% of Failures)
Excessive play in the steering, worn track rod ends, or noisy wheel bearings will all fail. If your steering feels vague, the car wanders on straight roads, or you can hear a humming noise that changes with speed, get it checked.
10. Fuel System Leaks (2% of Failures)
Any fuel leak is an immediate fail. Check under your car for any wet patches or fuel smell. Older vehicles and diesels are more prone to fuel line deterioration.
How to Give Yourself the Best Chance
The best approach is to do a quick walk-around check a week before your MOT. Test all the lights, check the tyres, look at the windscreen, and listen for any unusual noises. If you spot anything, get it sorted before the test rather than paying for a retest.
At AVS Bransgore, we offer MOT testing Monday to Sunday and you can book online through our website. We will always give you an honest assessment — we would rather help you pass than profit from a fail.
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