How to start a car with a dead key fob

A flat fob battery stops the remote and keyless functions, but almost every car has a backup.

Getting in

Smart keys contain a mechanical emergency key. Release it (usually a slide or button on the fob) and use the door lock, which on some cars is hidden under a small cap on the driver's door handle.

Starting a push-button car

The immobiliser chip in the fob doesn't need the battery. Most push-button cars have a backup: holding the fob against the start button, or placing it in a marked spot or slot (often in the console or cup holder) while you press the brake and the start button. The exact location is in your owner's manual under “if the key battery is discharged.”

Keyed cars

If your car uses a traditional key in the ignition, a dead remote battery doesn't stop it starting; only lock/unlock buttons are affected.

If it still won't start

Check whether the dash lights come on. If nothing powers up, the vehicle's 12-volt battery is the likelier problem, not the fob.

Then replace the fob battery: find your battery by make and model.