Is it lost, or just flat?
A smart key with a dying battery behaves exactly like a missing one: the car says "key not detected" and will not start. Before assuming it is gone, try a new coin cell in the fob, and try holding the fob right against the start button or in the marked backup spot in the console. If the car starts, the fob is fine and only the battery needed changing. Our guide to chip keys and fobs explains the backup spot.
If there is a spare
Use it, and have a replacement made while you still have one. Adding a second smart key to a car that already has a working one is a routine programming job and far simpler than doing it with none.
If every smart key is gone
The car has to be put into a mode that accepts a new key, and on many makes that involves a security procedure or a built-in waiting period designed to stop thieves programming their own key. A new fob with the right frequency and chip for the car is programmed to the immobilizer, the emergency blade inside it is cut to the door lock, and the car starts with it. Some very recent models can only be programmed by the dealer, which is why the year, make and model come first.
Delete the lost fob
A lost smart key is not just a key, it is a way to open and start the car without touching it. When the new one is programmed, ask for the missing fob to be deleted from the car's memory. After that, anyone who finds it has a piece of plastic.
What to have ready
- Your ID and the registration or title for the car.
- The year, make and model, and ideally the VIN, visible through the windshield.
- Where the car is parked. It does not need to move.
Our key fob replacement and all keys lost pages cover the service in detail across the Santa Clarita and San Fernando Valleys.
Questions people ask
Can a push-to-start car be driven without the fob?
No. The car has to detect a programmed fob to start. The emergency blade inside the fob only opens the door.
Do I need the car towed to the dealer?
Usually not. Most models are programmed on site. A handful of recent ones are dealer-only, and we say so from the year, make and model.
Can I buy a smart key online and have it programmed?
Sometimes. It must match the car exactly and must not be a used fob locked to another vehicle. Send us the details before buying.
Will the lost fob still start my car?
Until it is deleted from the car's memory, yes. Ask for the deletion when the new key is programmed.