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Powertrain fault code

P0505: Idle Air Control System

Monitor

Usually drivable, but the engine may stall at idle.

What P0505 means

The engine's idle speed is not where the computer expects it.

Common causes

  • Dirty throttle body or idle valve
  • Vacuum leak
  • Faulty idle control valve

What to check first

  1. Clean the throttle body.
  2. Check for vacuum leaks.

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Read your car's codes yourself, free

Plug a cheap ELM327 OBD-II adapter into the port under the dashboard and open the scan tool: Chrome or Edge on a computer with a USB adapter, or Chrome on Android with a Bluetooth LE adapter. It reads and clears codes and shows emissions readiness. It does not work on iPhone.

Open the free scan tool

Need help with P0505?

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Related codes

P0506P0507

General guidance only, not a diagnosis. A qualified mechanic should confirm the cause before you replace parts.