P0505
Medium SeverityIdle Air Control System
Engine System
P0505 — Instant Answer
Idle Air Control System
Severity: MEDIUM SEVERITY
Meaning: The idle air control (IAC) valve is not maintaining proper idle speed.
Safe to drive? Usually yes with caution, but confirm root cause before long trips.
Estimated repair cost: $10 - $80
Most common causes:
- 1. Carbon-clogged IAC valve (35-45% of cases)
- 2. Failed IAC valve (10-25% of cases)
- 3. Vacuum leak affecting idle (10-25% of cases)
- 4. Dirty throttle body (10-25% of cases)
Symptoms
- ⚠️Erratic idle speed
- ⚠️Stalling when coming to a stop
- ⚠️High idle
- ⚠️Hunting idle
Common Causes
How to Diagnose P0505
- 1Clean IAC valve and port
- 2Clean throttle body
- 3Check for vacuum leaks
- 4Replace IAC if cleaning does not help
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Exact Vehicle Hubs
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Related Codes
Frequently Asked Questions
- Can I clean the IAC valve?
- Yes — remove it and spray the pintle and port with throttle body cleaner. This fixes P0505 about 60% of the time.
- What is normal idle speed?
- Most engines idle at 600-800 RPM when warm. Higher or lower than this range indicates an idle control problem.
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Author & Review
Written by AllOEMManuals Editorial Team. Reviewed by ASE-certified technicians and updated with factory-reference checks for fitment-sensitive steps.
This guide was drafted with AI assistance and reviewed for accuracy by a human editor.
Last updated: 2026-05-07