Increasing automobile theft worldwide forces automobile manufacturers to develop new methods day by day. Now, in addition to alarm systems, there is a need for security systems that completely immobilize cars. After mechanical locks connected to elements such as steering wheel, handbrake, gear lever and clutch pedal, automobile security systems that electronically lock the engines of cars and also known as immobilizers have been developed. The immobilizer, which has now become a world standard, is installed on millions of vehicles every year. It is used as a standard accessory in many cars.

It consists of a main unit with the immobilizer, system computer and circuit breaker relays, a reader antenna located near the vehicle's ignition key slot, and an electronic key inserted near the ignition key. The electronic key in the ignition switch is charged when the reader enters the magnetic field created by the radio frequency waves sent by the antenna. In this way, the electronic key sends the previously saved password to the reader antenna from a distance of 5-10 cm, without the need for any energy source, via the radio transmitter inside.
The reader antenna compares this password with the existing passwords in the system's data bank, and after confirming the accuracy of the password, it releases the engine's vital ignition, starter and fuel pump circuits, thus allowing the engine to start. All of these processes take place in as little as one-tenth of a second, without the driver even knowing. 20 seconds after the key is removed from the ignition, these three circuits of the engine are automatically disabled by the system.

The fact that the immobilizer is more reliable, safer, more useful, more durable, smaller, and cheaper than similar systems used against automobile theft has enabled this system to be adopted very quickly all over the world. In addition, the ability of the electronic ID card not to be copied, its ability to be read from a distance, its durability not to be affected by electromagnetic interference or X-rays, and the fact that it does not require a battery or other internal power source, therefore, it does not require maintenance and repair are other factors that make this system so successful.

It is known by almost everyone that no security system can be 100% successful. The main purpose is to complicate the thief's job, to deter him and to make him turn to a car without an immobilizer. As a matter of fact, the rate of theft decreased by 90% in models fitted with immobilizers. Also, none of them have been stolen by disabling the immobilizer. The stolen cars were either towed away or the thief stole the driver's ignition key with the electronic ID card and started the car.