OBD2 Code P0505: Idle Air Control System Malfunction
The P0505 code means Idle Air Control System Malfunction. Estimated repair cost: $50 – $300.
✅ OK TO DRIVE (short term). Have it diagnosed at your next convenience. Monitor for new symptoms.
📋 Diagnostic Reference
| OBD2 Code | P0505 |
| Category | Powertrain |
| Severity | Check Soon |
| Repair Cost | $50 – $300 |
| Can You Drive? | ✅ Yes — diagnose at your convenience |
🔍 Symptoms
- Engine stalling at stop lights
- idle surging
- RPM dropping too low when AC kicks on
⚠️ Most Likely Causes (in order of probability)
- Faulty IAC valve
- carbon buildup in throttle body
- vacuum leak
- dirty IAC passages
🛠️ Diagnostic Procedure
Step 1: Clean throttle body and IAC valve passages with carb cleaner
Clean throttle body and IAC valve passages with carb cleaner
Step 2: Test IAC valve with multimeter
Test IAC valve with multimeter
Step 3: Check for vacuum leaks
Check for vacuum leaks
Step 4: Replace IAC valve if cleaning doesn't work.
Replace IAC valve if cleaning doesn't work.
ASE Certified Review: This diagnostic guide has been reviewed by an ASE-certified master technician. Diagnostic steps follow industry best practices per SAE J1979 and OEM service procedures. Always verify with a qualified mechanic before performing repairs.
Technician's Notes: Cleaning the throttle body and IAC passages fixes 70% of P0505 codes. Use throttle body cleaner only.
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Data Sources: Diagnostic information compiled from SAE J1979 OBD2 standards, OEM service manuals, and ASE master technician field experience. Reviewed for technical accuracy. Repair cost ranges are national estimates and vary by location. Always verify with a qualified mechanic.