Test NF-6B - Checking Oxygen (O2) Sensor Switching (Locked Lean)

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION. For appropriate wiring diagram, see WIRING DIAGRAMS at end of article.

Allow engine to idle. Inspect engine for vacuum leaks. Repair vacuum leaks as required. Perform VERIFICATION PROCEDURE VER-2. If vacuum leaks do not exist, read O2 sensor signal voltage using DRB-II.
If voltage is more than .1 volt, go to step 4). If voltage is less than .1 volt, turn ignition switch to OFF position. Disconnect O2 sensor and Single Board Engine Controller (SBEC) connectors. Place DRB-II in ohmmeter mode. Probe SBEC 60-pin connector terminal No. 41 (Black/Dark Green wire).
If resistance is less than 10 ohms, repair Black/Dark Green wire for a short to ground. Perform VERIFICATION PROCEDURE VER-2. If resistance is more than 10 ohms, replace O2 sensor. Perform VERIFICATION PROCEDURE VER-2.
If voltage is more than .1 volt, turn engine off. Replace O2 sensor. After replacing O2 sensor, turn ignition switch to ON position. Using DRB-II, reset adaptive fuel memory. Start engine, and allow it to reach normal operating temperature.
Read O2 sensor state. If O2 sensor state is switching, repair is complete. Perform VERIFICATION PROCEDURE VER-2. If O2 sensor state is not switching, perform TEST NF-13A.