Sensor/System Checks

WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Check the Heated Oxygen Sensors (HO2S) for proper operation. The HO2S should respond quickly to different throttle positions. If not, inspect the HO2S for silicone or other contaminants from fuel or use of improper RTV sealant. The sensors may have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). Silicone contamination causes a false high signal voltage (rich exhaust indicated). The Powertrain Control Module (PCM) will reduce the amount of fuel delivered to the engine.
Check the Manifold Absolute Pressure (MAP) sensor for proper operation. See DTC P0106: MAP SYSTEM PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.0L AURORA article.
Check the Throttle Position (TP) sensor and related wiring. See DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.0L AURORA article.
Check the Exhaust Gas Recirculation (EGR) system for proper operation. See EXHAUST GAS RECIRCULATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 4.0L AURORA article.