The most common MOT failures in the UK, and how to avoid them
2 July 2026·5 min read
The same few areas fail most cars
Year after year the same handful of areas sit at the top: lamps and signalling, tyres and wheels, brakes, suspension, then exhaust and emissions. These are wear items with predictable lives, not random breakdowns, so most failures can be prevented.
Roadworthy's MOT Stats page ranks every area live, with fail and advisory counts for each, so you can see what the fleet is struggling with right now.
- Lamps, reflectors and signalling: the clear leader every year
- Tyres: tread, damage and pressures
- Brakes: discs, pads, pipes and performance
- Suspension: bushes, arms, drop links and ball joints
- Steering, then exhaust and emissions: usually close together
Lights: the bulb that fails the whole car
One blown bulb, often a brake light or number-plate light, is enough to fail the test. The part costs a few pounds and takes minutes to fit, but you only notice it when someone is behind you.
Run the two-person light check from the preparation checklist once a month and this whole category of failure all but disappears.
Tyres: the 1.6mm rule
You need at least 1.6mm across the central three-quarters in one band. Testers also look for cuts, bulges, mismatched sizes across an axle and exposed cords. It is all visible if you look, and bald tyres are an offence on their own, so the MOT is not the only place this catches up with you.
Brakes and suspension: the expensive middle
Brake and suspension work costs more because it is labour heavy: seized calipers, worn discs, perished bushes and split gaiters. Two habits keep the bill down. Catch parts at the advisory stage, when a knock over a bump or a juddering pedal tells you something is due, and do not ignore a warning light.