A vehicle immobilizer is a security device designed to prevent a car from being started without the correct key or authorization. It works by disabling essential components, such as the ignition system or fuel pump, making it difficult for thieves to drive away with the vehicle. Immobilizers are commonly integrated into modern car keys or key fobs. These systems enhance vehicle security by using electronic codes that must match for the engine to start. If an unauthorized key is used, the immobilizer will trigger, ensuring that the vehicle remains stationary. Many insurance companies offer discounts for cars equipped with immobilizers due to their effectiveness in reducing theft.