From previous post with autozone link on testing O2 sensor.
"Disconnect the HO2S.
Measure the resistance between PWR and GND terminals of the sensor. Resistance should be approximately 6 ohms at 68�°F (20�°C). If resistance is not within specification, the sensor's heater element is faulty.
With the HO2S connected and engine running, measure the voltage with a Digital Volt-Ohmmeter (DVOM) between terminals HO2S and SIG RTN (GND) of the oxygen sensor connector. Voltage should fluctuate between 0.01-1.1 volts. If voltage fluctuation is slow or voltage is not within specification, the sensor may be faulty."
