P0505 Code: Idle Air Control System
P0505 means a fault in the idle air control system — the ECM can’t maintain the target idle speed.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $60 – $400
- Time to fix
- 1-3 hours
What it means
Common causes are a carbon-clogged idle air control valve or throttle body, a vacuum leak, or a faulty IAC. This is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer OBD-II vehicle — cars, trucks, and modern fuel-injected motorcycles — from any manufacturer (Toyota, Honda, Ford and the rest). Read it with any OBD-II scanner; the meaning is the same across brands, though the exact repair can vary by engine.
Symptoms
- Check engine light on
- Rough, high, or low idle; stalling
- Hard starting
How to fix it
- 1
Clean the IAC and throttle body
1. Clean the idle air control valve and throttle bore. 2. Check for vacuum leaks. 3. Replace the IAC if faulty, then clear the code.
Frequently asked questions
Why does my car stall at idle with P0505?
The idle-air system can’t feed the right amount of air at idle, so it stalls or hunts. Cleaning the IAC/throttle body often fixes it.
Last updated July 16, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.