Diagnostic Aids

WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. 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.
The correct 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 air flow sensor.
A tampered or damaged throttle stop screw.
A tampered or damaged throttle plate, throttle shaft, or throttle linkage.
A skewed high TP sensor.
Excessive deposits in IAC passage or on IAC pintle.
Excessive deposits in throttle bore or on throttle plate.
Vacuum leaks.
A high or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - 4.0L AURORA article.