High Or Low Idle

NOTE: Unless otherwise indicated, see appropriate SYSTEM & COMPONENT TESTING article for testing procedures.

Check idle speed adjustment. See IDLE SPEED, IGNITION TIMING & IDLE MIXTURE RATIO ADJUSTMENT in ON-VEHICLE ADJUSTMENTS article.
Check throttle position sensor adjustment.
Check IACV-AAC valve circuit.
Check electric throttle control actuator.
Check Throttle Position (TP) sensor circuit.
Check accelerator pedal position sensor circuit.
Check IACV-FICD valve circuit.
Check EGR system.
Check Engine Coolant Temperature (ECT) sensor circuit.
Check power steering oil pressure switch circuit.
Check ECM.
Check intake valve timing control solenoid valve circuit.
Check PNP switch circuit.
Check refrigerant pressure sensor circuit.
Check electrical load signal circuit.
Check air conditioner circuit.
Check fuel pressure regulator. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.
Check EVAP system.
Check PCV system.
Check air leakage from air duct.
Check electric throttle control actuator.
Check air leakage from intake manifold, collector and gasket.
Check thermostat.
Check cooling fan.