What each test shows
Every MOT entry gives you four things: the date, the result, the mileage and the defects. Read them together, test by test, rather than just checking that the latest certificate is valid.
Each defect is sorted into one of four categories: - Dangerous: a fail, and the car must not be driven - Major: a fail - Minor: a pass, but recorded - Advisory: a pass, but a warning to watch
A pass with a long advisory list means the car got through but may need work soon. Ask the seller what's been done.
Mileage should rise steadily. The UK average is about 7,100 miles a year, so a sudden jump or a drop between two tests is worth a closer look. A drop is the classic sign of a clocked odometer, and you can check it on our mileage check.
Patterns to look for
Read an MOT history for patterns, not single results. Look for four things: the same fault failing again, a long advisory list at the last test, mileage that doesn't rise steadily, and gaps with no test at all.
A repeat fault is your first warning. One fail that's been fixed is normal. The same fault coming back suggests a patch, not a fix. Advisories pass, but a long list at the last test means bills soon. Common ones are tyres near the legal limit, worn or pitted brake discs, perishing tyres and thin brake pads. Ask the seller what's been done.
Mileage should climb steadily. The UK average is about 7,100 miles a year, so check the readings between tests. A drop between MOTs is the classic sign of clocking, and selling a car with the wrong mileage declared is an offence. Gaps matter too. A car needs an MOT every year after its first, so a long stretch with no test needs an answer. It may have been off the road under a SORN, which means it must stay off public roads.
Using it to decide
Walk away if the mileage has gone down between tests, or if the same serious fault keeps failing. Negotiate when the problems are wear and tear you can price in. Decide before you view the car.
A drop in mileage between MOTs is the classic sign of clocking, and selling a car without declaring the mileage is wrong is an offence. Walk away too if the same major or dangerous fault keeps coming back, as the repair may never have worked. If there's a gap with no test at all, ask the seller why. A SORN explains a car off the road, but if they can't give a clear answer, move on.
A long advisory list at the last test is usually a negotiating point. Worn tyres close to the 1.6mm legal limit, pitted brake discs, cracking tyres and thin brake pads are all costs you'll face soon. Ask the seller to fix them before you buy, or take the cost of the work off the price. Check the tyres and pads yourself, as the list only shows what the tester saw.