Ownership

Buying a used car: the checks worth paying for before you hand over money

What to inspect yourself, what a diagnostic scan reveals that a test drive will not, and the paperwork that should make you walk away from an otherwise good car.

Published 9 May 2026By Motor Servicing6 min read
Short answer

Before buying a used car, check the paperwork first, then the body and tyres, then drive it from cold. A diagnostic scan reveals stored fault codes and cleared-code history that a test drive cannot, and mismatched or missing service records are the most common reason to walk away from an otherwise good car.

Before you view

  • Run the registration through the DVLA MOT history service. Free, and it shows every advisory and failure, plus recorded mileage at each test.
  • Look for mileage that jumps or stalls between tests. Both are worth an explanation.
  • Read the advisories chronologically. A recurring advisory that never becomes a repair tells you how the car was maintained.
  • Check the V5C matches the seller's name and address, and that the VIN on the document will match the car.

The visual checks that matter

  • Panel gaps and paint finish. Inconsistent gaps or mismatched texture indicate accident repair.
  • Tyres. Four different brands is not necessarily bad. Uneven wear across a single tyre is, because it points to alignment or suspension.
  • Under the oil cap. Mayonnaise-like residue can mean a head gasket issue, though it can also just be short-journey condensation.
  • Cold start. Insist on starting the car from genuinely cold. A warmed-up engine hides smoke, rattles and difficult starting.
  • Boot floor and spare well. The first place rust and repair evidence appear.

The test drive

Twenty minutes minimum, mixed roads, and with the radio off. What you are listening and feeling for:

  • Steering pulling under braking, or a pulsing pedal
  • Clutch bite point unusually high, or engine revs rising without acceleration
  • Knocks over bumps, which usually mean suspension bushes or drop links
  • Gearchange quality, particularly on automatics from cold
  • Warning lights that appear after a few miles rather than at start-up

What a diagnostic scan shows that a drive does not

A scan reads stored and pending fault codes, including ones that have not yet triggered a warning light. It also shows readiness monitors: if they have all been recently reset, someone cleared the codes shortly before you arrived, which is worth knowing.

On a diesel it reads DPF soot loading and regeneration history. On any car it reads battery health and charging system data. A mobile diagnostic health check at the seller's address costs a fraction of what it saves when it finds something.

Paperwork and history

  • Service records that match the MOT mileage timeline
  • Cambelt replacement evidence if the car is at or past its interval
  • Receipts for major work, not just a claim that it was done
  • Number of previous keepers against the car's age
  • An outstanding finance check before any money moves

See our guide to what a service history is worth for how to read a record properly.

When to walk away

Walk away if the seller will not let you start the car from cold, if the V5C name does not match, if the service history is claimed but absent, or if the answer to any direct question is vague. None of those are negotiating positions. They are information.

There is always another car. There is rarely another chance to un-buy this one.

Frequently asked

On anything over a few thousand pounds, yes. The cost is small relative to a gearbox, a DPF or a cambelt you did not know about.

We can carry out a diagnostic health check at an address with the owner's permission, on private land. It reads stored codes, live data and battery health.

Missing service history combined with a seller who cannot explain the gap. Everything else is usually negotiable.

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