Common reasons cars fail their MOT

MOT failures tend to come from the same handful of areas, and some of them are things you can check yourself before the test. Here’s what the official figures say, what to look out for, and what happens if your car does fail.

What the DVSA figures show

According to the DVSA’s MOT testing data for April 2025 to March 2026, 27.5% of MOTs on cars and light vans failed at the first attempt. These were the areas that most often caused a fail, shown as the share of all tests:

• Lamps, reflectors and electrical equipment: 10.4%
• Suspension: 8.9%
• Tyres: 6.2%
• Brakes: 6.1%
• Visibility (windscreen, wipers, washers and mirrors): 4.3%

Lights and electrics

Blown bulbs are the classic MOT fail, and the easiest to avoid: switch everything on and walk round the car before the test. The tester also checks headlight aim, the colour of the lights, and that lenses aren’t badly damaged. Fitting LED or HID bulbs into headlights designed for halogen bulbs is a fail on cars first used from 1 April 1986.

Dashboard warning lights count too. If the engine management, ABS, airbag, stability control or power steering light shows a fault, the car will fail.

Suspension

Suspension faults are harder to spot from the driveway because most of the parts are under the car. The MOT looks for broken or seriously weakened springs, shock absorbers leaking badly, and worn joints and bushes. Knocks or clonks over bumps, a car that wanders or pulls, or tyres wearing unevenly are all clues worth mentioning when you book.

Tyres and brakes

Tyres need at least 1.6mm of tread across the central three-quarters, all the way round, and no cuts down to the cords, bulges or lumps. A tread depth gauge costs a few pounds and takes the guesswork out of it.

Brakes are tested for how well they work and checked for wear, leaks and damage. Grinding or squealing, a pedal that feels soft or goes further than usual, or a car that pulls to one side under braking all need looking at, MOT or not.

Visibility

Windscreen damage bigger than 10mm in the 290mm-wide strip in front of the driver, centred on the steering wheel, can fail, as can damage bigger than 40mm anywhere else in the area the wipers sweep. Worn wiper blades, washers that don’t work or run dry, and missing or broken mirrors are all on the list too. Topping up the screenwash is the simplest MOT prep there is.

If your car fails

A car fails if the test finds any ‘dangerous’ or ‘major’ defects. It may also get ‘minor’ defects or ‘advisories’, which don’t fail it but are worth keeping an eye on. When we test your vehicle, we explain every major defect and advisory, give you our honest, impartial opinion on it, and then price any work needed.

You can only drive a failed car away if your current MOT is still valid and no dangerous defects were found. Driving a car that failed for a dangerous defect can mean a fine of up to £2,500, a driving ban and 3 penalty points. If your MOT has already run out, you can only drive the car to have the defects fixed or to a pre-arranged MOT test.

If you think the result is wrong, GOV.UK explains how to appeal an MOT result.

Getting a retest

After a fail, you have 10 working days to bring the vehicle back for a retest. After that, a completely new test is needed, so it’s worth getting the work booked in quickly. We can do the repairs here in our own workshop.

Don’t ignore the advisories

Advisories are the tester’s way of saying something is wearing and will need attention soon. Tyres close to the limit, light corrosion or a brake pipe starting to rust can turn into next year’s fail, or a problem before then. You can see the advisories from previous tests on GOV.UK’s MOT history service, which is also a useful check when you’re buying a used car.

Useful links

• MOTs
• Car repairs
• How to prepare for your MOT
• MOT test result and driving a failed car (GOV.UK)
• Retests after a repair (GOV.UK)
• MOT inspection manual for cars (GOV.UK)