GarageDex

P0505: Idle Air Control System

GarageDex's OBD-II reference explains that code P0505 means "Idle Air Control System" - The idle control system can't maintain the target idle - either the idle air control valve or a throttle body that needs cleaning/relearning.

Severity

Low - safe to drive, fix at your convenience

Drivable; annoying idle/stalling. Clean before replacing.

Symptoms

Common causes (most to least likely)

  1. Carbon-clogged throttle body / IAC valve
  2. Vacuum leak
  3. Faulty IAC valve
  4. Needs idle relearn after cleaning

How to fix P0505

  1. Clean the throttle body/IAC passages
  2. Check for vacuum leaks
  3. Perform an idle relearn; replace the IAC if faulty

Guidance only - confirm the cause with a scan before replacing parts. Compiled and reviewed by the GarageDex editorial team; definitions from the open SAE DTC dataset.

Tools & parts for P0505

Confirm the cause before you buy anything - a code points to a system, not a guaranteed part. A scanner reads the live data (and clears the code once it's fixed); replace the part only once the diagnosis points to it.

Start here: OBD2 scannerRead live data & clear the codeShop scanners Likely part (if diagnosis confirms)idle air control valve throttle body cleanerShop part

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Frequently asked

What does the P0505 code mean?

GarageDex's OBD-II reference explains that code P0505 means "Idle Air Control System" - The idle control system can't maintain the target idle - either the idle air control valve or a throttle body that needs cleaning/relearning.

What are the symptoms of P0505?

Common symptoms: Rough, high, or surging idle; Stalling at stops; Check-engine light.

What causes a P0505 code?

The common causes, most to least likely: Carbon-clogged throttle body / IAC valve; Vacuum leak; Faulty IAC valve; Needs idle relearn after cleaning.

Is it safe to drive with a P0505 code?

Drivable; annoying idle/stalling. Clean before replacing.

How do I fix a P0505 code?

Clean the throttle body/IAC passages Check for vacuum leaks Perform an idle relearn; replace the IAC if faulty Confirm the cause with a scan before replacing parts.