Idle Air Control (IAC) Valve

Warm engine to normal operating temp. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in ADJUSTMENTS - 2.0L (TURBO) article. Apply parking brake and place transaxle in Neutral.
With engine idling, disconnect electrical connector from IAC valve located on lower area of throttle body. Engine RPM should increase to at least 1000 RPM. Reinstall electrical connector on IAC valve.
Ensure engine returns to proper idle speed. If engine does not return to proper idle speed, check IAC valve resistance and operation.
To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve. Using ohmmeter, measure resistance between terminal B+ and each remaining terminal. See Fig 1. Replace IAC valve if resistance is not 19.3-22.3 ohms at 68°F (20°C).
To check IAC valve operation, remove IAC valve from throttle body. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. See Fig 2. Replace IAC valve if defective.
If IAC valve resistance is correct and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. The ECM is located on driver's side rear corner of engine bay. See wiring diagram in the WIRING DIAGRAMS article.

Fig 1: Checking IAC Valve Resistance

Fig 2: Checking IAC Valve Operation