P0505: Idle Air Control System Malfunction
Can you still drive? Yes, but the engine may stall unexpectedly at stops. Be prepared to use the brake firmly and restart if stalling occurs.
What Does P0505 Mean?
Code P0505 indicates a malfunction in the idle air control system. The IAC valve controls airflow around the closed throttle plate to maintain proper idle speed. When the system malfunctions, the engine may idle too high, too low, or erratically. On newer vehicles with electronic throttle control, this code relates to the throttle body idle position control.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Carbon buildup in IAC valve or throttle body
- Failed IAC valve motor
- Vacuum leak affecting idle control
- Dirty throttle body
- Faulty IAC wiring or connector
Symptoms
- Check engine light on
- Erratic idle speed
- Engine stalling at idle
- High idle speed
- Idle speed fluctuates up and down
Diagnostic Steps
- 1Clean throttle body and IAC passages thoroughly
- 2Test IAC valve operation with scan tool bidirectional control
- 3Check IAC valve wiring and connector
- 4Inspect for vacuum leaks that could affect idle
- 5Monitor idle air control position with scan tool
- 6Check for proper throttle plate closure
Recommended Parts & Tools
idle air control valve
throttle body cleaner
intake gasket
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $50 - $400 |
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Frequently Asked Questions
Can cleaning the throttle body fix P0505?
Yes, in many cases cleaning the throttle body and IAC passages with throttle body cleaner resolves the issue without replacing any parts.
What is an idle air control valve?
The IAC valve is a small motor-driven valve that controls airflow around the closed throttle plate. It adjusts idle speed based on engine load from accessories like AC and power steering.
Community Fix Reports
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