No original car key? How a locksmith makes one from scratch

How does a new key get made with no key to copy?

A modern car key does two separate things, and both can be recreated from the car itself.

It turns the lock. The blade's pattern comes from a code that every lock is built to. A locksmith can find that code through the vehicle's records using the VIN, or by decoding a lock on the car, often a door cylinder. With the code, a key machine cuts a blade that turns the doors and the ignition.

It tells the engine it is allowed to run. Most cars on the road have an immobilizer. A small transponder chip in the key head has to be recognised by the car, or the engine won't start no matter how well the blade is cut. Programming equipment plugs into the car's diagnostic port to register the new key.

Neither step needs a tow. Both happen where the car is parked.

What do I need to bring?

These protect you as much as they speed things up:

• Photo ID in your name.
• Proof of ownership or permission to use the car, such as the registration or insurance papers. If they are in the glovebox of the locked car, mention it on the call.
• The VIN. It is on the registration and on a plate where the dashboard meets the windshield on the driver's side, visible from outside.
• Year, make, model and trim, and whether the car is push-to-start or has a turn key.

Anyone willing to make a key to your car without checking who owns it would make one for a thief just as readily. The ID check is there for your benefit.

Why won't a freshly cut key start the car?

Because the blade and the chip are separate. A copy cut from a photo or at a hardware kiosk might open the driver's door, but without a programmed chip the immobilizer keeps the engine off.

The three key styles you are most likely to have:

Most smart keys hide an emergency blade inside, and that gets cut too, so a flat fob battery doesn't leave you stranded. If your fob works but cuts out in the cold or damp, that is a different and simpler problem: see key fob not working in cold weather.

Which situations take longer?

Most everyday cars are routine work. A few things add steps:

• Recent security systems. Some newer models need additional security access or a set procedure before a key can be added.
• Starting from zero. With no working key at all, the car has to be put into a learning mode without one, which takes longer than adding a spare to a key you already have.
• Damage from a theft attempt. A forced ignition or broken steering column may need repair before any new key will work.
• A seized door cylinder. Years of road salt can corrode the lock on the driver's door. If yours has been stiff or hasn't turned in a long time, tell us, because it affects how we approach the car.

That is why the year, make, model and trim come up on the first call. It lets us explain what your car needs before we arrive.

No keys at all? The first hour

Before the new key, a few steps that matter:

1. Retrace your route. Pockets, bags, the last shop or restaurant, the bus or the ferry, a taxi or rideshare.
2. Lock the car if you can. If the keys went missing near it, don't leave it open for whoever picks them up.
3. Think about what else was on the ring. House keys, a garage remote or anything with your address on it is the bigger worry. Read should I change locks after losing keys.
4. If the keys were stolen, report it and call your insurer before anything else.
5. Ask for the lost key to be erased. On many cars, programming the new key is also the moment to remove the old one from the car's memory.

Once you are driving again, have a spare made. Copying a working key is far simpler than starting from nothing, and nobody wants to repeat this on a wet February night in a lot with the wind coming off the water.

If the key is fine but the lock is iced over or seized with salt, see frozen car lock: what to do.

Can the key be made where the car is parked?

Yes. That is what a mobile service is for. The cutting machine and the programming equipment travel with the locksmith, so the key is made and tested at the car, whether it is in a downtown parkade, a driveway in Clayton Park or a lot in Dartmouth. To book, see car key replacement.