How to read an MOT history before buying a used car

Published 13 September 2026 · 4 min read · Reviewed against official sources

The MOT history is the single most useful free document in a used car purchase, and most buyers either do not look at it or glance at the pass/fail column and stop. Read properly, it tells you how the car has been driven, how it has been maintained, whether the mileage is honest, and what it is likely to cost you in the first year. Here is how to read it like someone who has been caught out before.

What the record actually is

Every MOT test in Great Britain and Northern Ireland is recorded centrally by the DVSA, and the history for any vehicle is public. For each test it shows the date, the result, the recorded mileage, and every defect the tester noted — split into failures that had to be fixed, and advisories that did not. Records go back to 2005 for most vehicles. The seller cannot edit it, and neither can a garage.

Start with the mileage column

Read the mileage at every test in order. It should rise steadily, and the annual increments should make sense for the car's use. Three patterns matter:

A drop. Mileage recorded lower than at a previous test. Occasionally this is a tester's typo, and the next reading will make that obvious. If it is not obviously a typo, the odometer has been replaced or the car has been clocked. Either way you need an explanation before going further.
A sudden change of pace. Five years at 15,000 miles a year followed by two years at 2,000 is a car whose life changed — a second car, an elderly owner, or a period off the road. None of those is bad, but it is worth understanding, because a car that sat for two years often needs tyres, brakes and a battery.
Mileage that does not match the advert. If the last MOT shows 84,000 and the advert says 78,000, stop.

Advisories are the real story

A fail tells you a fault existed on a specific day and was fixed. An advisory tells you a fault was developing and was not fixed — the tester saw it, noted it, and passed the car anyway. What you want to know is what happened next.

Look for advisories that appear on one test and are absent from the next. That usually means the owner acted on them — a good sign. Now look for advisories that appear on consecutive tests, year after year: "corrosion to rear subframe, not excessive", repeated three times. That is an owner who ignored the tester, and the fault has had three years to get worse. It will be your problem, not theirs.

The advisories that matter most for cost:

Corrosion — especially to structural components: subframes, sills, chassis rails, suspension mounting points. Cosmetic rust is annoying; structural rust becomes a failure and then a scrap decision.
Oil leaks — "slight oil leak" repeated over several years is an engine or gearbox seal that will need doing.
Brake pipes, suspension components, bushes — wear items that are cheap individually but add up when a car has been neglected.
Tyres close to the legal limit — at the last test, tells you what you will be buying immediately.

Gaps in the record

An MOT is annual once the car is three years old. A gap of more than about 13 months between tests means the car was off the road, was driven without a valid MOT, or both. Sometimes there is a benign reason — a long overseas posting, a restoration. Often there is not. A car that was driven without an MOT was almost certainly also driven without valid insurance, since most policies require a current MOT, and its maintenance during that period is unknown.

Similarly, a car whose most recent MOT is many months old, with a test due imminently, was possibly sold by someone who did not fancy their chances of passing it. Ask the seller to put a fresh MOT on it as a condition of sale. If they refuse, that is information.

Fails that were fixed the same day

A fail followed by a pass on the same date is normal — the garage found a fault, fixed it, retested. But read what failed. A failure for a headlight bulb is trivial. A failure for excessive corrosion that was passed two hours later suggests a repair done quickly to get a certificate rather than to fix the car properly. Structural welding is not a two-hour job.

Cross-checking against the seller's story

Once you have read the history, you know things the seller may not expect you to know. Use that. If the advert says "full service history" and the MOT shows the same brake advisory for four years, those two things do not sit together. If the seller says the clutch was replaced last year and the MOT that year shows an advisory for clutch judder, ask for the invoice. The history does not prove dishonesty; it gives you specific questions, and honest sellers answer specific questions easily.

What the history cannot tell you

It records only what an MOT tester is required to check. It says nothing about the engine's internal condition, the gearbox, the air conditioning, electrical faults, cambelt changes, or whether the car has been in an accident that was repaired to a good cosmetic standard. It is one document among several — an HPI-style check for finance and write-off history, a physical inspection, and a test drive are the others. But it is the free one, it is official, and a buyer who reads it properly is a buyer who is much harder to mislead.

A checklist to run before you view

Does the mileage rise consistently, with no drops?
Are there advisories that repeat across multiple tests?
Is any advisory structural — corrosion to subframe, sills, chassis?
Are there gaps of more than 13 months?
When is the next MOT due, and will the seller renew it?
Does the last recorded mileage match the advert?

Six questions, ten minutes, and you walk in knowing more about the car than most sellers assume you do.