P0505Medium SeverityEngine

Idle Air Control System Malfunction

What This Means

The idle air control (IAC) system circuit has a malfunction. The IAC valve regulates the amount of air bypassing the throttle plate to control engine idle speed.

Common Symptoms

Erratic idle speed
Engine stalling at idle
Idle speed too high or too low
Rough idle especially when cold

Common Causes

Carbon-clogged IAC valve
Faulty IAC valve motor
Vacuum leak
Dirty throttle body
Wiring issue to IAC valve

Estimated Repair Cost

$50 – $400

Parts and labor (varies by vehicle and location)

Difficulty:Easy

Need This Fixed?

Find certified mechanics near you who can diagnose and repair P0505.

Find a Shop Near You

Search Another Code

For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.