Replaced O2 Sensor, now won't start
 

2001 with 6 cylinder with california emissions and 4 O2 sensors. Rough idle, surges at 70 mph, check engine light comes on. OBD reads O2 sensor bank 2 sensor 2. Drive for week, light comes back on, have OBD read again to make sure its the same thing, it was. Replaced 02 sensor today (major pain in the a$$) and now it will not even come close to starting. Made sure my connections were good, eveything looks right. HELP!

Make sure the O2 sensor wires are not melted the the exhaust and causing a fuse to blow.

New NTK sensor is fine, pulled it out. Replaced it with the old one and engine fired up immediately. Double checked part number, its correct.

weird, it should still start even with the 02 sensor unplugged

That is exactly what I would think to.

I have the same vehicle, 01 GC, 4.0l CA Emissions w/ the 4 O2s. When I got the code to replace them, I also had a fuse blow out on mine. Dont remember the name of the fuse but it was in the O2 sensor circuit. May want to check that.