Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- High resistance in an IAC circuit.
- Correct PCV valve, properly installed, and properly operating.
- Proper operation and installation of all air intake components.
- Proper installation and operation of Mass Airflow (MAF) sensor, if equipped.
- Tampered or damaged throttle stop screw.
- Tampered or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
- Skewed high TP sensor.
- Excessive deposits in IAC passage or on IAC pintle.
- Excessive deposits in throttle bore or on throttle plate.
- Vacuum leaks.
- High or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by IAC valve.
If the problem is intermittent, See INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.