A transponder key, if not programmed can turn the engine over but not start the car.
All modern cars have transponder chips embedded in the key or remote control. Its always best to have a spare if your car needs a transponder key or remote control to start your vehicle.
Car keys with chips can be programmed using special programmers.
The vehicle locksmith company can make replacement transponder keys and remote controls for many makes and models. If you need a replacement key and you are in Essex London Kent and Hertfordshire then we can help.