Most Common MOT Failures & Repair Costs
37% of cars fail their MOT. Here are the top 10 reasons — and what each one costs to fix. Most can be spotted (and some fixed) before you book the test.
| # | Failure Reason | % of Failures | Typical Repair Cost | DIY Fix? |
|---|---|---|---|---|
| 1 | Lighting & Signalling | 30% | £5–80 | Yes |
| 2 | Suspension | 25% | £200–600 | No |
| 3 | Brakes | 18% | £150–400 | No |
| 4 | Tyres | 15% | £60–200 per tyre | No |
| 5 | Emissions | 10% | £100–500+ | No |
| 6 | Driver's View of the Road | 8% | £15–350 | Yes |
| 7 | Steering | 6% | £150–400 | No |
| 8 | Fuel & Exhaust | 5% | £80–300 | No |
| 9 | Body & Structure | 4% | £100–1,000+ | No |
| 10 | Seatbelts & Airbags | 2% | £50–200 | No |
Detailed Breakdown
Lighting & Signalling
30% of failuresWhat fails: Blown bulbs, cracked lenses, misaligned headlights, number plate light, brake lights
Typical repair cost: £5–80
💡 Pre-MOT tip: Walk around your car with someone pressing the brake/indicators. A £2 bulb saves a retest.
Suspension
25% of failuresWhat fails: Worn shock absorbers, broken springs, damaged ball joints, worn bushes
Typical repair cost: £200–600
💡 Pre-MOT tip: Bouncing test: push down hard on each corner — if it bounces more than twice, shocks are worn.
Brakes
18% of failuresWhat fails: Worn pads, corroded discs, seized calipers, handbrake not holding, brake fluid leak
Typical repair cost: £150–400
💡 Pre-MOT tip: Listen for squealing or grinding. If the car pulls to one side under braking, get it checked.
Tyres
15% of failuresWhat fails: Below 1.6mm tread, uneven wear, bulges, cuts, wrong size
Typical repair cost: £60–200 per tyre
💡 Pre-MOT tip: Check tread with a 20p coin — if the outer band is visible, the tyre is below legal limit.
Emissions
10% of failuresWhat fails: High CO2, catalytic converter failure, diesel particulate filter (DPF) blocked, engine management light on
Typical repair cost: £100–500+
💡 Pre-MOT tip: A 30-minute motorway drive before the test helps clear the DPF and catalytic converter.
Driver's View of the Road
8% of failuresWhat fails: Cracked windscreen in driver's line of sight, worn wipers, obstructed view
Typical repair cost: £15–350
💡 Pre-MOT tip: Replace wiper blades (£10–20) and check for windscreen chips in the swept area.
Steering
6% of failuresWhat fails: Worn track rod ends, power steering leak, excessive play in steering wheel
Typical repair cost: £150–400
💡 Pre-MOT tip: With the engine running, rock the steering wheel — any clunking or excessive play needs checking.
Fuel & Exhaust
5% of failuresWhat fails: Exhaust leaks, corroded pipes, missing heat shields, fuel cap not sealing
Typical repair cost: £80–300
💡 Pre-MOT tip: Listen for blowing sounds under the car. A loose exhaust is loud and obvious.
Body & Structure
4% of failuresWhat fails: Rust within 30cm of structural points, sharp edges, damaged sills, corroded subframe
Typical repair cost: £100–1,000+
💡 Pre-MOT tip: Check wheel arches, sills, and under the boot for rust bubbles. Structural rust is an instant fail.
Seatbelts & Airbags
2% of failuresWhat fails: Frayed belt, buckle not locking, airbag warning light on, missing belts
Typical repair cost: £50–200
💡 Pre-MOT tip: Pull each seatbelt fully out and check for fraying. Make sure the airbag light goes off after starting.
Frequently Asked Questions
What is the most common reason for MOT failure?
Lighting and signalling is the most common MOT failure reason, accounting for around 30% of all failures. This includes blown bulbs, cracked lenses, and misaligned headlights.
How much does it cost to fix a failed MOT?
The average MOT repair bill is £150–£300. Simple fixes like bulbs cost £5–20, while major failures like brake discs and suspension can cost £300–600+.
Can I drive my car if it fails the MOT?
If your car has a 'dangerous' failure, you cannot legally drive it. For 'major' failures, you can drive it only to a pre-booked garage for repair. 'Minor' failures (advisories) are noted but you still pass.
What percentage of cars fail their MOT?
Around 37% of cars fail their first MOT attempt. The failure rate increases with age — 20% for 3-year-old cars, rising to over 50% for cars over 12 years old.