Trouble codes › P0505

P0505 Idle Air Control System

Fuel and air

P0505 means the engine's idle speed isn't responding properly, often a dirty throttle body or idle air control valve.

The engine computer controls idle speed, either with an idle air control (IAC) valve or, on newer cars, the electronic throttle. P0505 means idle speed isn't responding the way it should.

Can I keep driving? Yes, but get it fixed soon.

Usually drivable, but the engine may stall when slowing down or stopping, which can be dangerous in traffic. Get it fixed soon.

Common causes

  1. A dirty or carbon-clogged idle air control valve or throttle body
  2. A failed IAC valve or its wiring
  3. A vacuum leak
  4. On electronic throttles, a dirty throttle body needing cleaning and an idle relearn

Symptoms

  • High, low or hunting idle
  • Stalling when coming to a stop
  • Hard starting

What to check first

  1. Clean the throttle body and, if equipped, the IAC valve and its passage with throttle body cleaner.
  2. Check for vacuum leaks.
  3. Check the IAC valve's connector and wiring.
  4. Do the idle relearn procedure your service information describes after cleaning.

What does P0505 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0505

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Related codes

General guidance for P0505 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.