You're right it is a 3 wire sensor. Thanks a bunch for the test suggestion. I'll perform that test this evening to see if the ECU is fried.

Last night I tested the o2 sensor out of circuit as the car warmed up and I thought I'd post the results here. Only problem is, I don't know the spec! Can anyone point me to them?

I only had the in-dash temp gauge to reference hence the imprecise temperatures listed below. These measurements were taken by probing the single sensor wire from the O2 sensor with my positive lead, and grounding to an unpainted door hinge bolt.

.0782V at 60c
.232V at 80c
.351V at 80c & increasing
.377V just at 80c
.380V just above 80c
.389V just above 80c
.396V just above 80c

The O2 sensor produced steadily increasing voltage as the car reached operating temp. I then blipped the throttle and voltage began to fluctuate cyclically, jumping around from 0 to ~1.9V to ~ 2-300MV. I shot a video of this but dont know how to embed on this forum so heres the link if you're interested: https://youtu.be/_XWJiZtsx3k

Last night just as I left the shop I went ahead and installed a new O2 sensor that I had lying around and also cleared the codes. I figured since I had the thing it would be an easy enough "test" to eliminate that variable.

Tonight I'll go for a drive and see if the code comes back. If it does I'll continue testing, starting by determining if the ECU is responding to the sensor.

Thanks!