You have lost every car key: what happens next

Before you call anyone: search properly

Keys turn up in the same handful of places with tedious regularity. Give it ten focused minutes.

• Coat and jacket pockets, including the coat you wore yesterday and the one in the car.
• The bag you carried, including the inner pocket you never use.
• Between and under the seats, under the mats, and in the trunk — keys get locked in cars far more often than they get lost outside them.
• Bins, the washing machine, the fridge, and any surface you set shopping down on.
• The last three places you paid for something. Call them; a huge number of keys are sitting behind a counter waiting for somebody to ask.
• If you were on public transport or at a venue, their lost property line.

Work out what kind of key you have lost

This decides the whole job, and it is the first thing a locksmith will ask.

• Mechanical key. Older vehicles. A plain cut blade, no electronics. Simplest case.
• Transponder key. A chip in the plastic head. The car's immobiliser reads it and only then lets the engine run. Cut but unprogrammed, the engine starts and dies within a second.
• Remote head or flip key. A cut blade and a remote in one body. Both halves have to be dealt with.
• Proximity or smart key. Push-to-start vehicles. The car senses the fob rather than reading a blade. There is nearly always an emergency blade hidden inside the fob and a physical keyhole on the driver's door, often under a small cap on the handle.

Gather the paperwork now, not later

Nobody legitimate will make a key for a car without establishing that it is yours, and you would not want them to — that check is the only thing standing between your car and the next person who fancies it.

• The vehicle identification number. Base of the windscreen on the driver's side, on the driver's doorjamb sticker, and on the registration and insurance card.
• Photo identification that matches the name on the paperwork.
• Registration, title or an insurance card in your name for that plate.
• Year, make and model, and whether the car is push-to-start.

What actually happens next

With no key to copy, the key has to be originated for your vehicle. There are two normal routes. Where the manufacturer holds the original cuts against the vehicle identification number, a key is produced to that code. Where it does not, the lock on the car is decoded and the key is cut to what the lock reveals.

Then the electronics. A transponder or proximity key has to be paired to the immobiliser through the vehicle's diagnostic port. Adding a key when you already hold one is quick; teaching a car to accept a key when it remembers none is a deliberately harder procedure, because that is exactly the moment a manufacturer wants to make life difficult for a thief. On some vehicles there is a built-in security wait — the car simply refuses to co-operate for a fixed period. That is by design.

What not to do

• Do not book a tow before you have asked a mobile locksmith. Towing a car with no key, to sit at a service department waiting for an appointment, is the long way round for most vehicles.
• Do not buy a key or fob online first. Some aftermarket units pair perfectly; others are the wrong chip family, or a convincing shell with electronics that will never talk to your car. Find out what your vehicle needs before you spend anything.
• Do not force the ignition or try to bypass it. Modern immobilisers make it pointless, and a forced ignition cylinder or a damaged steering column adds a serious repair to a job that did not need one.
• Do not break a window to get to the paperwork. An automotive locksmith can open the car without damage as part of the same visit.
• Do not use anybody who does not ask for your identification. If they will make a key for your car without checking, they will do it for the next person too. See how to tell if a locksmith is legitimate.

When it is a call-a-pro moment

Effectively as soon as you are sure the keys are gone. There is no home remedy for an originated, programmed car key. The useful question is not whether to call, but who: a mobile automotive locksmith who comes to the car, or a dealer who needs the car brought to them.

What a locksmith will do at the car

1. Check your identification and your ownership documents.
2. Open the vehicle without damage if it is locked.
3. Originate the blade — cut to code from the vehicle identification number, or by decoding the door lock or ignition.
4. Pair the transponder or proximity key to the immobiliser, and program the remote functions.
5. Erase the lost keys from the vehicle's memory if you ask for it — essential if the keys were stolen.
6. Test the new key in the driver's door, the ignition or start button, and the trunk, with you watching.

That is our car key replacement work, and it happens where the car is standing.

Afterwards

• Have a spare made. This is the whole lesson. One key is a plan with no backup.
• Store the spare somewhere separate — not the same bag, not the same hook, and not in the car.
• Write down the key code and the vehicle identification number and keep them somewhere safe at home. It makes any future job faster.
• If the keys were stolen, get the old ones erased and think about what else was on the ring.