An immobilizer is a security device installed in vehicles to prevent unauthorized starting of the engine. It works by disabling the engine's ignition 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 part of their standard security features. When the key or fob is inserted, it sends a unique code to the vehicle's computer system. If the code matches, the engine can start; if not, the vehicle remains immobilized, making it difficult for thieves to drive away.