DTC P0505: Idle Air Control (IAC) System Malfunction: Condition

DTC is set when engine idle speed is 100 RPM lower than predetermined when IAC valve opening is about 100 percent. DTC also is set when engine idle speed is 200 RPM higher than predetermined when IAC valve opening is about zero percent. DTC is also set when IAC valve monitor voltage is high. MIL is illuminated when Power Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• IAC valve malfunction.
• Air intake system plugged, leaking or fast idle control system malfunction.
• Vehicle Speed Sensor (VSS) malfunction.
• Mechanical engine malfunction.
• Excessive engine load.
• PCM malfunction.