The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingRegistration
In case of tire pressure warning ecu
replacement
Read id stored in the old ecu using the intelligent
tester.
In case of tire pressure warning valve and
transmitter and/or tire pressure warning
ecu replacement
Read the id written on the tire pressure monitor
valve.
...
Antenna location and effective range
Antenna location
Antennas outside the cabin
Antennas inside the cabin
Antenna outside the luggage
compartment
Effective range (areas within which the electronic key is
detected)
When locking or unlocking
the doors
The system can be operated
when the electronic key is with ...
Data list / active test
Read data list
Hint:
Using the intelligent tester's data list allows switch,
sensor, actuator and other item values to be read without
removing any parts. Reading the data list early in
troubleshooting is one way to save time.
Connect the intelligent tester (with can vim) to the
...