The main areas tested
Here's what the tester checks, and where cars most often fail.
- Lights and electrics: headlights, indicators, brake lights and horn. The most common failure, at 9.9% of tests.
- Suspension: springs, shock absorbers and joints. Fails in 7.9% of tests.
- Brakes: discs, pads and the handbrake. Fails in 5.9% of tests.
- Tyres and wheels: tread depth and damage. Fails in 5.5% of tests.
- Steering: play in the wheel and worn joints.
- Seat belts: condition, fixings and operation.
- Body and structure: corrosion and damage to the frame.
- Exhaust and emissions: leaks, noise and what comes out of the pipe.
- Mirrors: secure and undamaged.
- Wipers and washers: they must clear the windscreen.
- Number plates: correct, readable and securely fixed.
Tyres need at least 1.6mm of tread across the central three-quarters, and brake pads fail below 1.5mm. Tyres worn close to the limit and brake discs worn or pitted are among the most common advisories, so look at these yourself before you hand over any money. For a full walk-round, use our used car checklist.
What an MOT doesn't check
An MOT doesn't check the engine, clutch or gearbox. A car can pass with a tired engine, a slipping clutch or a gearbox that crunches into second. The test covers these parts only as far as they affect safety or emissions. Faults that go beyond that can be expensive, so you need to check them yourself.
An MOT isn't a service. It doesn't change oil, filters or fluids, and it doesn't show whether the car has been looked after. Ask the seller for service receipts, and check the car's MOT history for advisories that were never fixed. A pass today doesn't guarantee the engine will last.
Before you pay, take a long test drive from cold. Listen for knocks, check the clutch doesn't slip under acceleration, and make sure the gears change smoothly. If you're unsure, pay for an independent inspection. The used car checklist covers the rest.
Results and what happens next
A car passes its MOT when it has no dangerous or major defects. Minor defects are recorded but don't cause a fail, and advisories are warnings about parts that will need attention soon. Since 20 May 2018, every defect falls into one of four categories:
- Dangerous: fail, and don't drive the car
- Major: fail
- Minor: pass, but recorded
- Advisory: pass, but a warning to keep an eye on
If your car fails, the certificate lists every reason. Get the faults fixed, then book a retest. Driving without a valid MOT can bring a fine of up to £1,000, unless you're driving to a booked MOT or to repairs. The maximum MOT fee for a car is £54.85, so a higher quote is worth questioning. Before you buy, check a car's past results at MOT history check.