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P0519 Powertrain

Idle Air Control System Performance

The idle air control system is electrically intact, but the actual idle airflow does not match the commanded value - typical for a sticky valve, intake leak, or carbon build-up around the throttle bore.

Affected components

  • Idle air control valve
  • Intake manifold
  • Throttle body

Common causes

  • High likelihood: IAC valve sticking due to carbon
  • Medium likelihood: Intake leak disturbs idle metering

Possible symptoms

  • Check engine light on
  • Idle speed too high, too low, or unstable
  • Possible stalling at idle or after cold start

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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