Most Common MOT Failure Reasons in South London
Understanding the most common MOT failure reasons can save you money and avoid the inconvenience of an unexpected failure. This guide covers the most frequently failed MOT items in South London.
Tyre tread depth
The most common MOT failure. UK law requires a minimum of 1.6mm tread depth across the central three-quarters of the tyre. Below this the tyre fails the MOT. The 20p coin test: insert a 20p coin into the tread groove — if the outer band is visible, the tyre is approaching or below the legal limit. Tyres with bulges, cuts to the cords, or damage that penetrates the cord structure also fail regardless of tread depth.
Lights
The second most common MOT failure. Any bulb failure — headlights, brake lights, indicators, rear fog light, number plate lights — causes a major failure. Headlight aim is also checked: incorrectly aimed headlights fail the test. LED or HID lights with a failed individual element also fail. Carry out a full lights check before your MOT by walking around the car with a helper.
Windscreen damage
A chip or crack in the driver's primary vision zone (the 290mm zone centred on the steering wheel, behind the swept wiper area) larger than 10mm will fail the MOT. Outside this zone, damage up to 40mm is acceptable. Cracks that impair the driver's view will fail regardless of size.
Brake performance
Brakes are tested on a roller — each axle is measured for braking force and the imbalance between left and right is calculated. A significant imbalance causes the vehicle to pull under braking and fails the test. Brake pad and disc condition is also visually inspected through the wheels.
Suspension and steering play
The tester rocks the wheels to check for play in ball joints, wheel bearings, and steering components. Excessive play causes a major failure. Anti-roll bar link failure — a very common and inexpensive repair — is also checked.
Common questions
How much does an MOT cost at KITH Cars?
£50 for all standard cars and light vehicles. The DVSA maximum is £54.85 — we charge less.
Is a free retest available if my car fails?
Yes — free retest within 10 working days on the failed items only.
Can I drive my car to the MOT without a valid MOT?
Yes — to a pre-booked appointment only, and directly back if it fails. Not for any other purpose.
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