P0505

What it means

This code means your car's computer has detected a problem with the system that controls your engine's idle speed. This system ensures your engine runs smoothly when your foot isn't on the gas pedal.

Is it safe to drive?

While you might be able to drive, an unstable idle can cause the engine to stall unexpectedly, especially at stops, which can be dangerous. It's best to address this issue promptly to prevent stalling and potential safety hazards.

Most likely causes

• Faulty Idle Air Control (IAC) Valve

  high

  The IAC valve can become clogged with carbon or fail electronically, preventing it from regulating idle speed.

• Vacuum Leaks

  medium

  Leaking vacuum hoses, intake manifold gaskets, or PCV system components can introduce unmetered air, disrupting idle.

• Dirty Throttle Body

  medium

  Carbon buildup around the throttle plate can restrict airflow at idle, causing erratic idle speeds.

• Wiring Harness Issues (open, short, corrosion)

  low

  Damaged wires or corroded connectors to the IAC valve or throttle body can disrupt control signals.

Related help

• Full P0505 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?