Lost Your Only Car Key? What to Do Next

Losing a spare is an annoyance. Losing the only key is a different problem: there is nothing to copy, and on most cars built in the last twenty-odd years the key isn't just a piece of metal. It has to match the locks and be recognized by the car. The good news is that it can be done without the car going anywhere. Here's what to do, step by step.

Step 1: Search properly before you replace it

Lost keys turn up more often than you'd think. Before you replace one, give the search a fair shot:

• Retrace your day in order, including stores, the gym, work and other people's cars.
• Call the places you visited. Keys that get handed in tend to sit at a front desk or in a lost-and-found box.
• Check coat pockets, bags, the laundry and the couch, and look inside the car through the windows.
• Ask anyone who drove the car recently.

If the key might have been stolen along with something showing your address, treat that differently: see Step 5.

Step 2: Work out what kind of key your car uses

The kind of key decides what the new one involves. If you have a photo of the key, or the owner's manual, check which of these it is:

• A plain metal key. Found on older cars. It only has to be cut to match.
• A transponder key. A metal blade with a thick plastic head that hides a small chip. The car reads the chip before it will start, so the key has to be cut and then programmed.
• A remote-head key or flip key. The key and the lock buttons in one piece. It needs cutting, and programming for both the chip and the remote.
• A smart key. A fob that stays in your pocket, for cars with a push-button start. The only cutting is the small backup blade inside, but the fob has to be programmed to the car.

If you're not sure which you have, the year, make and model usually answer it, and we can tell you on the phone.

Step 3: Find the details we'll ask for

A new key starts with the car's details, and having them ready saves a second call:

1. The VIN, the 17-character vehicle identification number. It's on a small plate where the dashboard meets the windshield on the driver's side, on a sticker in the driver's door frame, and on your insurance card.
2. The year, make and model, and the trim if you know it.
3. Where the car is, and whether it's locked. If it's locked, it has to be opened first, and that's part of the same visit.
4. How many keys you want. One key is how this happened. Two is better.

Step 4: What making a new key involves

With no key to copy, a new one has to be cut to match your car's locks and then introduced to the car so it's accepted. Both happen at the vehicle. Programming uses the car's own diagnostic port, which is why the car has to be there, but it doesn't have to go anywhere.

Blanks and fobs sold online are tempting, but they don't always match your exact car, and some can't be programmed at all once they've been used. If you already bought one, tell us what it is when you call.

Step 5: If the key was stolen

A key taken with your bag or wallet is more than a lost key, because whoever has it may also know where the car is parked. Report the theft to the police, and mention it when you call us, so removing the old key from the car's memory is part of the plan from the start.

• Check whether anything else on the ring opens something: your house, your office, a mailbox.
• Change those locks too, or have them rekeyed, if the ring had your address on it.

How to never be here again

• Keep a spare somewhere safe that isn't the car.
• Label nothing. A key ring with your address or your plate number helps whoever finds it more than it helps you.
• Replace a worn key before it fails. A cracked head, a loose chip or a bent blade is a key on its way out.
• Look after the fob. A dying battery is easy to mistake for a bad fob. Our guide on a key fob that stops working walks through the difference.