P1605 – Rough Idle / Idle Control Malfunction (Toyota)

Description

The ECM detected improper idle control operation resulting in unstable engine speed during idle conditions.

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Symptoms

  • Rough idle
  • Engine shaking
  • Idle fluctuations
  • Possible stalling
  • Poor acceleration

Causes

  • Dirty throttle body
  • Faulty idle air control valve
  • Vacuum leaks
  • Weak ignition components
  • ECM idle learning lost

Diagnosis

  • Inspect throttle body
  • Check vacuum lines
  • Test ignition coils
  • Check idle control valve
  • Perform idle relearn

Repair

  • Clean throttle body
  • Repair vacuum leaks
  • Replace IAC valve
  • Replace coils if needed

Related Problems

Related Fault Codes