P0518 Fault Code

Idle Air Control Circuit Intermittent

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0518 fault code indicates an issue with the Idle Air Control (IAC) circuit, specifically that it is intermittent. This means that the system experiences irregularities in controlling the engine's idle speed, which can lead to performance problems. The IAC is crucial for maintaining the correct idle speed by regulating the amount of air entering the engine while it is running under various conditions.

What are the symptoms of the P0518 code?

Common symptoms associated with the P0518 fault code include:

• Erratic or unstable idle speed.
• Engine stalling during idle or low-speed operation.
• Rough engine performance, especially when stopping or slowing down.
• Check Engine Light illumination on the dashboard.

What causes the P0518 code?

Possible causes for the P0518 code include:

• A defective Idle Air Control Valve.
• Wiring issues such as frayed or shorted wires in the IAC circuit.
• Poor electrical connections at the IAC or the engine control module (ECM).
• Faulty engine control unit (ECU) or software glitches.
• Dirt or carbon buildup in the IAC valve affecting its operation.

How to fix P0518?

To resolve the P0518 fault code, follow these steps:

• Inspect the IAC valve for operational issues and replace it if necessary.
• Check wiring and connectors in the IAC circuit for signs of damage or corrosion, and repair as needed.
• Clean the IAC valve and its ports to remove any dirt or carbon buildup.
• Use a diagnostic scanner to verify if there are any software updates available for the ECU, and apply them if necessary.
• After repairs, clear the fault codes and test drive the vehicle to ensure the problem is resolved.