Test NF-6A - Checking Oxygen (O2) Sensor Switching
- Allow engine to reach normal operating temperature. Using DRB-II, read O2 sensor state. If O2 sensor state is switching, system is functioning okay. Test is complete. If O2 sensor state is not switching, check if O2 sensor is locked on lean. If O2 sensor is locked on lean, perform TEST NF-6B. If O2 sensor is not locked on lean, go to next step.
- Turn engine off. Remove upper intake manifold (intake plenum). Refer to 3.3L & 3.8L V6 article in ENGINES. Turn ignition switch to ON position. Using DRB-II, actuate fuel system test. Inspect injectors for fuel leakage. If any injectors are leaking, replace leaking injectors and/or "O" rings as necessary. Perform VERIFICATION PROCEDURE VER-3. If injectors are not leaking, go to next step.
- Using DRB-II, stop fuel system test. Turn ignition switch to OFF position. Install upper intake manifold. Inspect air cleaner filter and inlet ducts for restrictions. If any restrictions exist, clear restricted air inlet system as necessary. Perform VERIFICATION PROCEDURE VER-3. If restrictions do not exist, perform TEST NF-13A.