P0505 - Idle Air Control System Malfunction
Idle control is not operating as expected.
Code first. Confirm symptoms and checks before pricing parts.
Explore Related Systems
Compare nearby repair families.
Common Next Steps
Turn the code into the next check.
Compare trims at idle, 2500 RPM, and cruise before pricing sensors.
Check intake boots, PCV hoses, and post-MAF leak paths.
Inspect MAF contamination and airflow data after intake leaks are considered.
Look for cracked ducts, loose clamps, and unmetered air after the MAF.
Related Inspection
Code Overview
Idle control is not operating as expected.
Common Causes
- Dirty throttle body or sticking throttle plate
- Idle air control valve failure on systems that use one
- Vacuum leak affecting idle control
- Idle relearn needed after battery or throttle service
Symptoms
- Idle speed hunts or will not stabilize
- Stalling or near-stall at stops
- Idle speed higher or lower than normal
Diagnostic Steps
- Inspect the intake tract and vacuum hoses for leaks
- Inspect and clean the throttle body if carbon buildup is present
- Test the idle air control valve if the system uses one
- Perform the idle relearn procedure if the vehicle requires it
Repair Difficulty
Moderate
General difficulty estimate for the most common repair path.
Likely Repairs & Cost Guides
Confirm the repair path before pricing parts.
Estimator-ready next step after the fault path is confirmed.
Related OBD Codes
Browse nearby codes when systems overlap.
Next Steps
Move from code to checks, then estimate.