Key Programming

A modern key is not a piece of cut metal. It is a transponder holding a short conversation with the immobiliser every time you press start. The blade turns the barrel, the chip is what lets the engine run, and programming is the work of teaching one end to accept the other.

Before any of that happens we establish that the car is yours. The registration in your name, or written authority from whoever it is registered to, plus your own identification. That is not a formality to be waived for someone in a hurry, and it applies to a simple spare as much as to a car that will not start. Key work on a vehicle whose owner has not been established is how a stolen car gets driven away looking legitimate, so the answer there is no.

Rolling code, sometimes called hopping code, means the key and the car agree a fresh number on every press and never send the same one twice. Capturing a transmission out of the air gains an attacker nothing, which is the whole point of it. It also means a spare cannot be copied. A new key has to be introduced through the immobiliser using the vehicle's own security access, and on most makes that is a timed and logged procedure rather than a five-minute clone.

All keys lost is the harder case and it is the one that usually calls. With nothing to copy from, the security data is read out of the immobiliser or the engine control unit itself, a key is written to match, and the old keys are deleted so anything that left with a previous driver stops working. Adding a spare while you still hold a working key is a far shorter job, which is the argument for doing it before you need to.

For a car that will not start, we come to the vehicle. A key job on a driveway, at a villa or in a car park is normal work, and there is no sense recovering a car that only needs a key.