Diagnostic Aids
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Check for the following conditions:
- High resistance in an IAC valve control circuit.
- The correct Positive Crankcase Ventilation (PCV) valve, properly installed and proper operation of the PCV valve.
- Proper operation and installation of all air intake components.
- Proper installation and operation of the Mass Airflow (MAF) sensor, if equipped.
- A tampered with or damaged throttle stop screw.
- A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
- A skewed high Throttle Position (TP) sensor.
- Excessive deposits in the IAC valve passage or on the IAC valve pintle.
- Excessive deposits in IAC valve passage or on IAC valve pintle.
- Excessive deposits in the throttle bore or on the throttle plate.
- Vacuum leaks
- A high or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by the IAC valve.
- High or unstable idle condition caused by a non-IAC system problem that cannot be overcome by IAC valve.
- If the problem is determined to be intermittent, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.1L CENTURY, GRAND PRIX & MALIBU article.