Rough, Unstable Or Incorrect Idle & Stalling: Sensor/System
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect for conditions which cause an incorrect idle speed. Check for throttle body tampering, excessive deposits, or damage. Check for restricted air intake system. Check for large vacuum leaks.
- Check the Positive Crankcase Ventilation (PCV) valve for proper operation. See POSITIVE CRANKCASE VENTILATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
- Check the Throttle Position (TP) sensor and related circuit wiring. See DTC P0123: TP SENSOR CIRCUIT - HIGH VOLTAGE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
- Check the Exhaust Gas Recirculation (EGR) system for proper operation. See .EXHAUST GAS RECIRCULATION under EMISSION SYSTEMS & SUB-SYSTEMS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
- Check the transaxle range switch input with the vehicle in Drive and the gear selector in Drive or Overdrive.