Transponder key and key fob operation in modern vehicles
https://bravo-wiki.win/index.php/Transponder_key_and_key_fob_operation_in_modern_vehicles
Modern vehicles use transponder keys and fobs that communicate wirelessly with the car's security system. When you press a button or approach the vehicle, the fob sends a unique coded signal to the transponder receiver, which verifies the code and unlocks the doors or allows the engine to start. This system helps prevent theft by making it difficult to duplicate the signal, though it can occasionally cause issues if the fob battery dies or the code needs resyncing.