The S-series made its debut as the first model Saturn released in 1991. The first two S-series vehicle's Saturn released were the SC and SL -- a two-door and four-door, respectively. In 1993 Saturn expanded the S-series lineup with the release of the SW station wagon. The 1999 Saturn S-series included the same three body styles -- SC coupe, SL sedan and SW station wagon. All three body styles came with a 100-horsepower, 1.9-liter engine standard and had an optional 124-horsepower, 1.9-liter engine. The idle air control valve is a motor-and-valve assembly that opens and closes to adjust the airflow into the intake manifold, which increases and decreases the idle.
Trace the Saturn's air intake tube towards the engine until you locate the throttle body, the metal component connecting the tube to the engine. Find the idle air control valve -- the cylindrical electronic component -- on the rear of the throttle body.
Press the locking button on the IAC valve wiring harness and pull the harness from the IAC valve. Remove the two IAC valve-retaining bolts, using a ratchet and socket. Pull the IAC valve from the throttle body.
Measure the distance between the new IAC valve's mounting flange and the tip of its metal plunger, using a ruler. If the distance between the flange and the tip of the plunger is greater than 1-1/8 inches, press the plunger toward the IAC valve with your finger until the distance is less than 1-1/8 inches.
Apply a thin coat of a thread-locking chemical onto the threads of the IAC valve-retaining bolt. Insert the plunger side of the IAC valve into the throttle body and hand-tighten the IAC valve-retaining bolts. Tighten the IAC valve-retaining bolts to 2 to 3 foot-pounds, using a torque wrench and socket. Plug the wiring harness into the IAC valve.
Reset the IAC valve's position by turning the Saturn's ignition to "Run," but do not start the vehicle. Allow the ignition to set in "Run" for about 20 seconds. Turn the ignition off for about 10 seconds and start the Saturn's engine.
Verify the Saturn's idle is stable. If not, repeat Step 5 to reset the IAC valve again.
Turn the vehicle off.
