P1612 – Immobilizer Communication Error (Toyota)

Description

The ECM detected a communication failure between the immobilizer system and the engine control module.

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Symptoms

  • No start condition
  • Security light on
  • Key not recognized
  • Intermittent start
  • Failsafe mode

Causes

  • Faulty immobilizer ECU
  • Wiring issues
  • Connector corrosion
  • Weak battery voltage
  • ECM communication fault

Diagnosis

  • Check wiring
  • Inspect connectors
  • Measure battery voltage
  • Test immobilizer ECU
  • Scan for related codes

Repair

  • Repair wiring
  • Clean connectors
  • Replace immobilizer ECU
  • Replace ECM if needed

Related Problems

Related Fault Codes