Diagnostic Aids

Inspect for the following conditions:

• High resistance in an IAC valve control circuit
• Restricted air intake system
• Proper operation and installation of all air intake components
• Collapsed, clogged, or loose air intake ducts
• A clogged air filter
• Proper operation of the mass air flow (MAF) sensor, if equipped
• A tampered with or damaged throttle stop screw
• A tampered with or damaged throttle plate, throttle shaft, or throttle linkage
• Objects blocking the IAC passage or throttle bore
• Excessive deposits in the IAC passage or on the IAC pintle
• Excessive deposits in the throttle bore or on the throttle plate
• Vacuum leaks
• A low or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. Refer to Symptoms - Engine Controls .

If the problem is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections .