P0519 Idle Air Control System Performance

• OBD2 Code: P0519
• Description: Idle Air Control System Performance
• Definition: This code indicates that the idle air control (IAC) system is not performing as expected. The IAC system regulates the engine’s idle speed by controlling the amount of air bypassing the throttle plate, and a malfunction can lead to irregular idling or stalling.

p0519 – Idle Air Control System Performance

Typical Severity: Moderate

Common Causes

p0519 – Idle Air Control System Performance

Common causes:

• Faulty idle air control valve
• Vacuum leaks in the intake system
• Dirty or clogged throttle body
• Electrical issues with the idle air control system circuit
• Engine mechanical problems affecting idle speed

 

Common Misdiagnosis

OBD2 Code: P0519

Description: Idle Air Control System Performance

Common Misdiagnosis: Replacing the idle air control (IAC) valve without checking for vacuum leaks or issues with the throttle body.

 

Common Diagnostic Steps

OBD2 Code: P0519

Description: Idle Air Control System Performance

• Check for any additional codes that may be present and address those first.
• Inspect the idle air control (IAC) valve for carbon buildup or damage. Clean or replace if necessary.
• Examine the IAC valve wiring and connectors for any signs of damage, corrosion, or disconnection. Repair as needed.
• Test the IAC valve operation using a multimeter to ensure it is receiving proper voltage and ground signals.
• Check for vacuum leaks around the intake manifold, throttle body, and associated hoses. Repair any leaks found.
• Inspect the throttle body for dirt or carbon deposits; clean if necessary.
• Verify that the engine coolant temperature sensor is functioning correctly, as it can affect idle speed control.
• If equipped with an electronic throttle control system, check for issues with the throttle position sensor or motor.
• Perform a thorough inspection of all related components in the idle air control system to ensure they are functioning properly.