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P1581 – Idle Speed Control Overshoot

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Symptoms

  • High idle
  • RPM flare
  • Poor fuel economy

Causes

  • Sticking IAC valve
  • Vacuum leak
  • Throttle body contamination

Diagnosis

  • Inspect IAC valve
  • Check vacuum lines
  • Inspect throttle body

Repair

  • Clean or replace IAC
  • Repair leaks
  • Clean throttle body
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