Checking Oxygen Sensor (O2S) Switching
NOTE:
For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION. For wiring diagrams, see WIRING DIAGRAMS - 2.5L TBI
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 O2 sensor 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 O2 sensor connector. Disconnect Powertrain Control Module (PCM) connector. Put scan tool in ohmmeter mode. Using scan tool, check resistance of O2 sensor connector Black/Dark Green wire.
- If resistance is less than 10 ohms, repair short to ground in Black/Dark Green wire. Perform TEST VER-2. If resistance is more than 10 ohms, replace O2 sensor. Perform TEST VER-2.
- Turn engine off. Replace O2 sensor. Turn ignition on. Using scan tool, reset adaptive fuel memory. Start engine. Allow engine to reach normal operating temperature.
- Using scan tool, read O2 sensor state. If O2 sensor state is switching, repair is complete. Perform TEST VER-2. If O2 sensor state is not switching, go to TEST NTC-15A.