An immobilizer is a security device installed in vehicles to prevent unauthorized starting. It works by disabling the engine or fuel system unless the correct key or fob is used. This technology helps reduce vehicle theft and enhances overall safety. Most modern vehicles come equipped with an immobilizer as a standard feature. When the key is inserted, a unique code is transmitted to the vehicle's computer. If the code matches, the engine starts; if not, the vehicle remains immobilized. This system is often part of a broader security strategy that may include alarms and tracking systems, such as GPS devices.