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 troubleshootingDisplaying a bluetooth®
device details
You can confirm and change the registered device details.
Bluetooth® device registration status
Display the “bluetooth* setup” screen.
*: Bluetooth is a registered trademark of bluetooth sig, inc.
Select the device.
Select “device info”.
Following screen is displayed:
...
Before refueling the vehicle
Close all the doors and windows, and turn the engine switch to the
“lock” position (vehicles without a smart key system) or off (vehicles
with a smart key system).
Confirm the type of fuel.
Fuel types
Unleaded gasoline (octane rating 87 [research octane number 91] or
higher)
Cauti ...
Checking monitor status
Perform monitor drive pattern
Connect the intelligent tester to the dlc3.
Turn the ignition switch and the tester on.
Clear the dtcs (see page es-35).
Run the vehicle in accordance with the applicable
drive pattern described in readiness monitor
drive pattern (see page es-19). Do ...