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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 59 (Smart Access System (For Start) - Diagnostic Codes & Symptom Tests (1 Of 2)) >> SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Start Function, Gasoline Model) >> DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [11/2021 - ] >> Description

DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [11/2021 - ]: Description

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If the communication line (IMI - EFIO) between the ECM and ID code box (immobilizer code ECU) is stuck high, the ECM will store this DTC.

DTC No. Detection Item DTC Detection Condition Trouble Area DTC Output from Priority Note
B279A-12 Engine Immobilizer System Circuit Short to Battery The communication line (IMI - EFIO) between the ECM and ID code box (immobilizer code ECU) is stuck high. (1 trip detection logic*)
  • ID code box (immobilizer code ECU)
  • ECM
  • Wire harness or connector
Engine A DTC output confirmation operation:
  1. Turn the ignition switch to ON and wait 6 seconds.
  1. *: Only output while a malfunction is present.
VEHICLE CONDITION AND FAIL-SAFE OPERATION WHEN MALFUNCTION DETECTED

Vehicle Condition when Malfunction Detected Fail-safe Operation when Malfunction Detected
Engine cannot be started Engine cannot be started
RELATED DATA LIST AND ACTIVE TEST

DTC No. Data List and Active Test
B279A-12 -