Test NTC-7B - Checking Oxygen Sensor (O2S) Switching

NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION. For wiring diagrams, see WIRING DIAGRAMS - 3.0L article in ENGINE PERFORMANCE.

Allow engine to idle. Inspect engine for vacuum leaks. Repair vacuum leaks as necessary. Perform TEST VER-2 . If no vacuum leaks exist, using scan tool, read oxygen sensor (O2S) signal voltage.
If voltage is more than 0.1 volt, go to step 4). If voltage is less than 0.1 volt, turn ignition off. Disconnect O2S connector. Disconnect Powertrain Control Module (PCM) connector. Put scan tool in ohmmeter mode. Using scan tool, check resistance of O2S connector Black/Dark Green wire (AA and AJ bodies) or Dark Green/White wire (AS body).
If resistance is less than 10 ohms, repair short to ground in appropriate wire. Perform TEST VER-2. If resistance is more than 10 ohms, replace O2S. Perform TEST VER-2.
Turn engine off. Replace O2S. Turn ignition on. Using scan tool, reset adaptive fuel memory. Start engine. Allow engine to reach normal operating temperature.
Using scan tool, read O2S state. If O2S state is switching, repair is complete. Perform TEST VER-2 . If O2S state is not switching, go to TEST NTC-15A .