What is an engine immobilizer on a 2007 Volvo 2.4 i S40?

An engine immobilizer on a 2007 Volvo 2.4i S40 is a security feature designed to prevent unauthorized starting of the vehicle. It works by disabling the engine's ignition or fuel system unless the correct key or fob, equipped with a transponder chip, is used. This system enhances vehicle security by making it difficult for thieves to hotwire the car. If the immobilizer does not recognize the key, the engine will not start, thereby deterring theft.