O2 Sensor Question

[arclite20]

How do i test the wires coming off the O2 sensor to decide which one is the one to connect to a and air/fuel ration gauge.I have a 97 Corolla CE.

[thespud]

How many wires does it have? If it is a one wire, that is the one to connect to the air/fuel guage, if it is a two, three or four you need a multi meter on low voltage.

Unplug the O2 sensor, turn the car to on (dont start it), put your multi meter on two of the terminals. A two wire, you will get ~+/- 0.9v. Whichever way tou get a positive voltage, connect the a/f meter to the positive wire (the red one on the multi meter usually). A three or four wire you will get +/- 12v on two of the terminals of the connector. This is the O2 sensor's internal heater, dont touch. On a Three wire, which ever you dont get 12v between the terminals, connect to the a/f meter. On four wires is the same as the two wire, once you've ratted out the heater wires.

Three and four wires are generally easy, as the two heater wires are usually the same colour, in my case black, but u need to check these anyway. The two others are polarity sensitive tho, so be wary of which you connect the a/f meter to.

[arclite20]

its a 2 wire

[thespud]

In that case, you need to find the positive wire, by connecting a multi meter to it, finding a positive voltage then connect the meter to the positive side of your multi meter. Two wires only have a positive and an earth wire.