Buying a Used Car? The Car Key Checklist Most Buyers Skip

Buyers inspect bodywork, tyres and service history, then drive away having barely glanced at the keys. Keys are one of the few faults that are trivially cheap to fix before the sale and expensive to fix afterwards. Run through these five checks before money changes hands.

1. Are there two working keys?

A car should come with two. Many used cars come with one, and "the spare is somewhere at home, I'll post it" is a spare that never arrives. A second key costs £120–£300 depending on the vehicle, so this is a legitimate £200 negotiating point — or ask the seller to supply one before collection.

2. Test every function on every key

Lock, unlock, boot release, panic button, and — critically — starting the engine. A key that opens the doors but will not start the car has a failed transponder and is not a working key.

3. Check for signs of a previous all-keys-lost job

Mismatched key styles, an unbranded aftermarket fob, or a shiny replacement lock barrel that does not match the wear on the rest of the car can all indicate a previous key loss or theft attempt. Not automatically a dealbreaker, but ask the question and look harder at the V5C history.

4. Ask how many keys have ever existed

This is the check almost nobody makes. If the car has had four previous owners, keys may still exist that you will never see. Anyone holding one can open and start your car. An auto locksmith can delete all unknown keys from the immobiliser and pair only the keys you physically hold — usually £60–£120 and worth every penny on any used purchase.

5. Check the key against the car's specification

If the advert says keyless entry and go, make sure the key actually is a proximity smart key and not a downgraded basic remote from a previous replacement. Downgraded keys are common on cars that have had a cheap key job done and mean the convenience feature you paid for no longer works.

After you buy

Our recommended first-week jobs on any used car: delete all unknown keys, and get a spare cut and coded so you are never in an all-keys-lost situation. Both can be done in one mobile visit. Call +44 7347 492822 with the registration for a fixed price.