MOT defects explained

All defects

• Ball joint worn

  Play has developed in a steering or suspension ball joint. Affects handling and tyre wear, and worsens over time.

  Typical repair: £120–£280

• Brake disc worn, pitted or scored

  The brake discs have surface wear. Braking is still effective, but the discs and usually the pads should be inspected soon.

  Typical repair: £180–£320

• Brake pads wearing thin

  Friction material on the pads is close to its limit. Straightforward to replace, and cheaper if done before the discs are damaged.

  Typical repair: £90–£200

• Braking efficiency below requirement

  The vehicle did not achieve the required braking force on test. This is a failure item and needs diagnosis before further use.

  Typical repair: £120–£450

• Corrosion in a structural area

  Rust has been found in or near a load-bearing area. Repair must be done properly by welding, not filled.

  Typical repair: £250–£1,200

• Emissions above the permitted limit

  The vehicle exceeded its emissions threshold. Causes range from a due service to a failing catalyst or sensor.

  Typical repair: £80–£900

• Exhaust leaking or insecure

  Gases are escaping before the tailpipe, or a section is loose. Can be a clamp and a joint, or a full section.

  Typical repair: £60–£350

• Headlamp aim incorrect

  The beam pattern is outside the permitted range, which can dazzle other drivers. Usually a quick adjustment.

  Typical repair: £20–£60

• Headlamp not working

  A headlamp did not illuminate on test. Usually a bulb, but can be wiring, a connector or a failed control module.

  Typical repair: £20–£120

• Lamp not working

  A side, brake, indicator, fog or registration plate lamp failed to operate. Typically a bulb or a corroded holder.

  Typical repair: £10–£80

• Mileage discrepancy

  A recorded odometer reading is lower than an earlier one. Check the original certificates, service invoices and the instrument history before drawing a conclusion — a fallen reading can be a data-entry error or a replaced instrument cluster, not necessarily alteration.

  Typical repair: Verification is usually free

• Play in the steering

  Excess movement has been found in the steering system. Needs diagnosis to identify which joint or rack is responsible.

  Typical repair: £150–£600

• Shock absorber defective

  A damper is leaking or no longer controlling the spring. Replaced in pairs across an axle to keep handling balanced.

  Typical repair: £180–£400

• Suspension arm bush worn

  A rubber suspension bush is deteriorating. It can cause knocking, uneven tyre wear and less precise steering as it worsens.

  Typical repair: £160–£300

• Tyre damaged or deteriorated

  The tyre has a cut, bulge or perishing sidewall. This cannot be repaired — the tyre needs replacing.

  Typical repair: £70–£160 per tyre

• Tyre worn close to the legal limit

  There is little usable tread left. Replace before it reaches the 1.6mm legal minimum across the central three-quarters of the tyre.

  Typical repair: £70–£140 per tyre

• Windscreen damaged in the swept area

  A chip or crack sits within the driver's field of view. Small chips can often be resin-repaired rather than replaced.

  Typical repair: £70–£350

• Wiper or washer not working properly

  The wipers or washers cannot clear the screen adequately. Usually blades, a blocked jet or a failed pump.

  Typical repair: £15–£120