I installed a 3 wire oxygen sensor in place of the old single wire sensor. I also have a AutoMeter air/fuel ratio gauge installed. When I tested everyting out for the first time today, saw most things were working, some not, now its troubleshooting time. First off I noticed the air/fuel gauge not working. I was going to check the wires later. I was checking the operation of other thiongs when my friend noticed the gauge started reading for a few seconds then cut back off. Another friend saw smoke comming from the o2 sensor. I immediately shut it off and jumped underneath, expecting to see burnt wires, but I didnt see anything out of the ordinary. I have never seen smoke from a sensor before. I got a brand new ACDelco sensor with an ACDelco replacement connector. The purple wire originally on the car was spliced to the A/F gauge and the respectine wire of the connector. One of the other wires of the connector is to 12v, the other to ground. I have the 12v coming from a 3 amp fused ignition source. The o2 sensor is tight in the exhaust bung. I used anti-sieze on the threads, and the sensor is free of any oil or debris. Is this correct? Anyone else seen this before?