What is Engine Immobilizer Technology? How does It work?

By CarsFellow 7 Min Read

An immobilizer is an electronic motor security system that prevents the engine from running unless the right key (transponder or intelligent stick) is present. Therefore, the vehicle may not be “hotwired” after entry, and therefore motor vehicle rubberizing is reduced.

Research has shown that the consistent use of immobilizers has reduced the car theft rate by 40%. There is an electronic chip in the engine control unit, which is used by the engine immobilizer.

The key transfers the electronic code to the vehicle engine management system (EMS). Suppose the driver inserts this digital key in the ignition switch or transfers the vehicle’s smart key fob. The only way to start the engine is if the code inside the key or Smart Key fob in the transponder chip matches the engine immobilizer code.

Main Components

The main components of an engine immobilizer re:

  • Key chain
  • Circuit breaker
  • Control block


In the new cars, an advanced system uses rolling/changing security codes. This system provides two-tier protection in BMW vehicles. A permanent personal code and a second code that changes.

The machine updates the second code each time the key begins and stores the key’s second code. The immobilizer reads the personal code first when the driver turns on the ignition. The second rolling code is then demanded.

Only then can the immobilizer give the engine management system another codified signal after these two codes have matched. The engine would not operate without this. Without the second safety code, and if anyone wants to shorten the ignition circuit, the engine will not start again. Thus, the risk of car theft reduces

The transponder chip cannot easily be duplicated because the key or Smart Key fob is incorporated. If the key or smart key fob is missing, the lost key can only be disabled by approved dealers. After testing the customer credentials, you can arrange for a new key from the manufacturer.


There are many advantages of engine immobilizer some of them are mentioned below;

  • Automatic working:

The biggest advantage of engine immobilization is that it works automatically. The car holder has not to activate it every time.

  • Steady and safe method:

Steady and safe immobilization technology prevents auto theft from heating or normal inflammatory methods.

  • Anti-theft alarm:

Engine immobilizer offers an anti-theft alarm, which is very helpful and useful.

  • Can be removed

One of the benefits of an engine immobilizer is that it can be easily removed and shifted. For instance, if you are buying a new vehicle, you can easily use the same immobilizer.


This system has a major downside considering its high reliability. When you use a key card or a keychain with a chip, a thief will steal them – and a new owner is in the car. You will use the replacement key if you lose the key (most devices are equipped with two copies).

However, this must be done to drive the car to a service station where the control unit can light. If not, the intruder will use the computer for his purposes.


Sometimes your engine may cause problems; these problems indicate that you may need to change or update your immobilizer. Some of the problems you may have with your engine immobilizer are;

  1. Unlocking problems:

You do not loosen the doors when you use your key to lock your car’s doors remotely. Regrettably, many modern cars do not have keyholes outside the door. Thus you cannot manually open them with your key.

It means you can’t go back into the car if you lock the doors from inside and then shut the doors as your key cannot open the doors. You should call a locksmith at this point to open the door.

  1. Engine Stops Working:

A general symptom that your engine immobilizer does not start at all is a problem. Several explanations may explain why the engine does not start when it is not for issues with the locking mechanisms.

However, if you have these problems and an engine that does not try to start, then either your immobilizer or the smart key itself will cause you a problem.

  1. Key Does Not Turn:

You can have issues with the transponder chip on the key fob if your key fob contains a physical key, which you can insert in the ignition and switch, and it does not budge. It doesn’t give the safety code to the car immobilizer for some reason.

It is mostly because of water damage (water and electronics do not mix) or actual chip disruption due to the fob collapse. Make sure to use the right fob for the car before purchasing a new key. Just because your spouse drives the same car make does not mean that your key fob works.

  1. Car Alarms:

Since an immobilizer’s main feature is to secure your vehicle, if something is wrong with it, your car alarm would not work.

How To Fix Malfunction

Many immobilizer problems can be solved easily by replacing the key fob battery. The safety code is transferred to the car immobilizer by several transponder keys rely on a small battery. Please take care to recharge your battery so that the transponder chip is not unintentionally harmed.


Purchasing an engine immobilizer is not easy as it seems. First of all, you should not go to the first store you enter, as a low-quality device might be selected.

Only after installation will the defect show. Hence, the time needed for returning the items will be paid for dismantling. It is recommended to purchase and install real estate in the car park. In this situation, the contractor is responsible for all aspects.

You should check the key aspects of different engine immobilizers and then choose what suits you best.

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