Car remote start systems use a coded pulse of radio signals to initiate a car's ignition sequence remotely when the remote starter's controller is activated. Remote starters are integrated into a car during production or added to a vehicle as an aftermarket modification with a security bypass module.
Many modern cars have security systems built into them to prevent unauthorized ignition unless the car key or a key fob is present, usually by requiring a code to unlock the ignition mechanism of the car that is stored in a chip integrated into the key or fob. While these systems are not an issue for remote start systems integrated by the manufacturer of the car, aftermarket systems often require a security bypass module that unlocks the ignition by mimicking the security system of the car. Manufacturers use different security designs, so the module required varies based on the make and model of the car.
Security is a serious concern for users of remote starter systems, as it is possible for a thief or other malicious individual to start the car without needing to gain physical access or keys. Most manufacturers of remote start systems incorporate security coding to prevent unauthorized users from starting a car, but the efficacy of some of the these systems is questionable. Some insurance companies refuse to underwrite policies for certain models of cars due to flaws in their remote start systems that make it easy for thieves to gain access.