GM Code 35 Idle Air Control Valve

CODE 35 - Idle Air Control Valve Problem or Idle Error

Trouble Code 35 indicates a problem with the Idle Air Control (IAC) circuit. It will be set when the closed throttle engine speed is 200 RPM above or below the desired (commanded) idle speed for 50 seconds. Possible causes include:

•  Vacuum Leak (High Idle) - Also check for binding of throttle blade or linkage.
•  System too lean (High Air/Fuel Ratio) - The idle speed may be too high or too low. Check for low regulated fuel pressure, water in the fuel, or a restricted injector.
•  System too rich (Low Air/Fuel Ratio) - The idle speed will be too low. May exhibit black smoke in exhaust. Check for high fuel pressure, leaking or sticking injector.
•  Foreign material in throttle body.
•  Faulty IAC Valve electrical connections.
•  Faulty PCV valve.
•  Faulty IAC.
•  Faulty ECM.

Trouble Code 35 is not used in the Turbo cars. If this code appears while a computer is connected to the ALDL connector, it is probably the result of a bad cable connection at the PC or the ALDL connector. Re-seat the cable connections.