Automotive keys aren’t simply just keys anymore. Car keys have become more advanced over the last two decades. Vehicle manufactures have implemented an electronic security immobiliser system into their cars which needs to be linked to a transponder chip inside the head of your car keys.
This transponder chip was programmed into the original set of car keys and has a unique code for each vehicle. Therefore, for the engine to start, the code on your keys, has to be linked with the vehicles immobiliser system.
If the transponder breaks or is lost, your vehicle will not start without that chip. The vehicle will need another transponder chip diagnostically programmed to its immobiliser system.
As a result, replacement car keys became more expensive and stealing vehicles became harder. If you only have one key to start your vehicle. It is a wise decision to have a spare key cut and programmed, to avoid the inconvenience of losing all the keys to your car. Having a spare key created is significantly cheaper than creating a new one, when no working keys are available.