P1601 – ECM Communication Error (Toyota)

Description

The ECM detected a communication failure within the control network, affecting data exchange between modules.

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Symptoms

  • Check engine light on
  • Intermittent stalling
  • Unresponsive throttle
  • Communication errors
  • Failsafe mode

Causes

  • Faulty ECM
  • CAN bus wiring issues
  • Loose connectors
  • Low battery voltage
  • Corroded grounds

Diagnosis

  • Scan for network faults
  • Check CAN wiring
  • Inspect connectors
  • Measure battery voltage
  • Test ECM communication

Repair

  • Repair wiring
  • Clean connectors
  • Restore grounds
  • Replace ECM if required

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