What Fails an MOT Most Often?
Most MOT failures aren’t “big engine problems”. They’re usually safety and maintenance items that build up over time — brakes, tyres, suspension, lights, warning lights and emissions. This guide shows the most common failures and how to avoid them.
Warning lights
Engine, ABS, airbag and traction control lights are common MOT fails. If your dash has a warning light on, get it scanned before the test.
Brakes & tyres
Worn pads/discs, uneven braking, low tread and damaged tyres are some of the biggest reasons vehicles fail.
What to send us
Reg + postcode + MOT date + any warning lights + any noises (squeak/knock/rumble) + any recent repairs.
Why cars fail when they “feel fine”
An MOT is a safety and emissions check — not a “does it still drive?” test. Many parts wear gradually, so the car can feel normal even when components are past legal limits.
Most common MOT failure areas
Brake pads / discs / imbalance
Worn pads/discs, seized sliders/calipers, and uneven braking performance are very common. (See: Brake Pads Worn • Brake Discs Worn)
Low tread or tyre damage
Low tread, sidewall cracks/bulges, puncture repairs in unsafe areas, or mismatched tyres can all fail.
Worn bushes / ball joints / shocks
Knocks, clunks or uneven tyre wear often trace back to suspension wear. (See: Suspension Knocking)
Play or vibration
Excess steering play or vibration can indicate worn components or wheel bearing issues. (See: Wheel Bearing Noise • Steering Wheel Shaking)
Bulbs, headlamp aim, wipers
Blown bulbs, poor headlamp aim, damaged lenses, worn wipers and windscreen issues are easy-to-miss fails.
Smoke, faults, DPF issues
Engine faults and diesel emissions issues can cause an MOT fail. (See: DPF Warning Light On • Smoke From Exhaust)
Quick checks before your MOT
1) Warning lights
If a warning light is on, fix it before your test. Even if the car drives fine, it can still fail. (See: Is it safe to drive with a warning light?)
2) Lights
Check headlights, brake lights, indicators, reverse and fog lights. Make sure lenses are clear and not cracked.
3) Tyres
Look for low tread, cuts, bulges, and uneven wear. If you can see cords or sidewall damage, don’t drive far.
4) Brakes & noises
Squeaks, grinding, pulling to one side, or knocking over bumps often indicates wear that may fail an MOT.
Common MOT fails and what they usually mean
MOT FAQs
In many cases, yes — especially engine management, ABS, airbag and stability/traction warnings. If a light is on, book diagnostics before your test.
Do a pre-MOT check: lights, tyres, warning lights, and basic brake/suspension inspection. Fixing small items early is cheaper than failing and retesting.
Many common MOT failure items can be repaired mobile — brakes, batteries, some suspension and diagnostics. Message your reg + postcode + MOT report and we’ll advise.
Local MOT help: AutoAid Mobile Mechanic covers Warrington and surrounding areas. If your MOT is coming up, send your reg + postcode + date and we’ll help you avoid a fail.