two are grounds, one is 12v for the heater, and the other is the signal output.


different cars are different as to what is what.....but i am sure someone has a wiring diagram (i do, but its at work....)

got a voltmeter? take it and backprobe to see which one (green or white) has 12v on it when you turn the key on. then, tap off of the other one.



and as a sidenote, i assume its probly an Autometer one? there are a few O2 sensors that they dont work with, and alot of Hondas use a different kind of O2. the best thing to do is to have an additional bung added and use an O2 that works with it, or get a wideband (but that is too much money for alot of people, even the DIY one the sensor for it has gone outrageous, to about 395 last i checked.)