Immobilizer - what is it in the car

As the main protection against car theft, most drivers use a popular alarm system. However, in recent years, the popularity of such a device as an immobilizer, what it is in the car, and how the device works, we consider in our article.

Premium-class foreign cars are often equipped with this device at the factory, and insurance companies are ready to provide a discount for CASCO policies to cars in which car owners have already installed such electronics. The high degree of security from radio interception makes it impossible for fraudsters armed with pirated scanners to work.


  • 1 What is an immobilizer
  • 2 Types of immobilizers
    • 2.1 Contact
    • 2.2 Contactless
    • 2.3 Mobile
  • 3 The right choice immobilizer
  • 4 Voluntary “immobilizer” lock

What is an immobilizer

The main objective of this device is to protect the car from theft. He does this by means of a break in the electrical circuit that ensures the operation of the ignition system, the fuel supply and the starter.

what is the immobilizer in the car

It is equipped with a more advanced intelligent system in contrast to the alarm system. Not for nothing with the English term, deciphering the electronic immobilizer, translated as "immobilizing".

Any immobilizer consists of the following elements:

  • Electronic control unit. Its task is to process the signals generated by auto nodes, decrypt them and give the necessary commands based on such data.
  • Electronic relay. Its functions include the electrical circuit break, through which the launch of the vehicle units is powered.
  • Fuel valve. Often installed on new models of systems to block the supply of gasoline or diesel fuel to the system.
  • Ignition key.

Do not lose the key, because without it the car will not start, because the recognition takes place on the chip embedded in such a key.

Types of immobilizers

According to the type of action, there are several variants of electronic blockers of cars. Consider how the immobilizer works in a car with various communications options.


To start the engine you will need to insert a key into a special socket on the car’s panel. Only after this operation is the reading of codes from the chip. This option is an early modification of the systems. On modern cars, it is less common.

how is a regular immobilizer mounted

Contact immobilizer installation

The disadvantage of this design is that the fraudster already knows the place of fixing the reader. At the same time, this class of immobilizers required to enter a code using a keyboard switch, which is an additional weak link in this chain. After all, the code of the hijacker could pick up yourself.

See also: How to make a stroboscope for cars with their own hands


With such devices, no codes need to be entered. The principle of operation of the immobilizer with a contactless system is based on the fact that it sends a signal to the key and receives a response from it. An electronic password is generated inside the service, and not by the user pressing a key.

How does the contactless immobilizer in the car

Contactless immobilizer items

A positive feature is the implicit presence of this security system. It cannot be recognized at a distance.

Similar services are divided by radius of action. In the case of a short distance for recall (often up to 20 cm), it will be necessary to insert the key with the chip into the signal distribution zone. For this, the key fob is brought to a certain place on the panel, and the automation allows starting the motor. The disadvantage of the design is such a key presentation. Fraudsters may notice the characteristic movement of the driver, which will indicate the presence of an electronic blocker.

A more modern staff immobilizer works at a distance of several meters. In this case, do not bring anything anywhere. The service independently recognizes the owner with the chip. The signal coding is carried out according to rather complicated protected algorithms. To intercept it and quickly decipher you will need unnecessarily expensive equipment operating at these frequencies. Power in the devices is passive, due to this, long autonomous work is ensured.


One of the latest developments in this area is blocking while driving. Even in that situation, when the hacker will have time to get into the car and retire for several tens or hundreds of meters, the motor will stall and prevent it from continuing. The fraudster will understand what an immobilizer is in a car only after the car stops in the middle of the road.

how to protect the full-time immobilizerThis option is relevant if the driver literally thrown out of the car, taking away the keys. However, it is required to keep the electronic key fob separate from the common bundle. A clear difference from other types is that the system blocks the supply of fuel, etc. on a running engine, not before it starts. This option will complicate hacking.

See also: How to charge a car battery without a charger

The right choice immobilizer

In order for this security system to give maximum effect, it is necessary to follow several rules:

  • to start the engine you will need to have at least two keys, one of which must be kept at home, and the second - separately from the entire bundle in your pocket;
  • it is necessary to carry out the installation of an electronic blocker at certified stations and not to announce this to outsiders;
  • Before use, you must be familiar with the instruction manual and wiring diagram;
  • write the number of the service center that installed the electronics in the phone in case of problems with the software;
  • in addition to the immobilizer in the car to install additional means of protection, for example, alarm.
how does the immobilizer in the car

Immobilizer operation scheme

Voluntary “immobilizer” lock

For various reasons, drivers have to temporarily refuse to work this system. In some cases this is due to incorrect functioning of the electronics, and sometimes its presence prevents the installation of additional anti-theft systems. To carry out this operation, you should not resort to outside masters or to independent intervention.

These actions can violate the integrity of the work of regular electrical appliances and then more expensive intervention will be required for repairs. Contact should be where the initial installation. In the same place they will be able to carry out diagnostics of the immobilizer's working capacity.