What does the O2 sensor want?
 

Or, what does the ECU want from the O2 sensor?

I have a 95 Civic with the 1.6 VTEC and I have an O2 sensor that codes a bad heater circuit, so I've been trying to remove it. I got the special socket and that's just been rounding it off. I WD40d it, torched it, and I can't get it to break loose. I have a replacement sensor, so I plugged that into the socket without screwing it into the exhaust, and the CEL goes off, and the car runs great.

So I'm wondering, with the sensor out in the air as opposed to in the exhaust, I'm assuming that it's reading high O2. My understanding is that the ECU will be calling for a richer mixture to try to cure the condition. That is not what I want. I'd rather have a lean condition for FE sake. (I really want the sensor reading the exhaust like it's supposed to do), but my question is for tweekers who trick the ECU into providing a lean burn, how is this done? And how badly will I screw things up if I run it this way for awhile?

First off, the o2 sensor sockets are almost all junk! snip the wires off with enough that you can crimp them back together if you really need to, then get a real, good socket for an impact wrench and get it off that way.
the o2 sensor doesn't start giving the engine a reading until it's 600F so your new sensor is telling the ecu that the sensor is good but you are going to burn up the heating element in it if you keep it plugged in without it being installed.

Thanks Ryland. I cut the wires and used an impact socket with a breaker bar, and it was still a bear to get it out of there, but I did it!

I'm still wondering how people trick their ECUs into giving a lean burn. You really have to go pretty far to get too lean around here with the low atmospheric pressure at 10,200 ft.