You should have 3 wires going to the O2 sensor; 2 together and one seperate (green I think). The two white? wires are the heater wires. Disconnect the single wire and, with a digital voltmeter, connect from the O2 sensor to ground to get your readins per the manual. 0.5 to 0.85 volts rings a bell for O2 sensor output near a fuel/air ratio around 14.7:1. Think of the O2 sensor as a battery who's fuel is oxygen which is then adjusted at your fuel distributer with a LONG 3mm (I think) allen wrench.

Remember, the O2 readings are invalid until it has reached operating temp (about 3-5 minutes of driving).