O2 Sensor Problem!!!

I posted this in the SW section but it really is for any 1.9 DOHC engine.

Ok.... Here is the deal. I have a 97' SW2 Auto. I keep getting a code P0134 on my code scanner. Swaped the exhaust manifold for the exhaust headers and downpipe from a 91' . The O2 Sensor from the 97' would not fit in the headers from the 91' so I got a new O2 sensor for the 91' headers. I have checked the voltage at the sensor. Fluctuates between .78-.89 while engine running. With the harness connected, it reads 1.01-1.09 and is pretty steady. The code is: "No activity O2 Sensor CKT. Bank 1 Sensor 1" Which is the front O2. Im sure the O2 sensor is fine. I have also replaced the heated O2 after the cat just to be sure it is ok as well. No matter what I do, I keep getting the code.
Can anyone tell me if, (for some strange reason that would not make any sense whatsoever) if there is any difference in refrence voltage for the 97' sensor and the 91' sensor?? From what I have read about O2's they all work the same (one wire all wor the same as one wire). The book I have says it should read 0.5 on harness KOEO. (Key On Engine Off) and the sensor should read 0.1-0.5 warmed up. I will check reading again and post them. Maybe someone with the same engine can check their readings compare with mine. Thanks in advance guys. As you can tell I am at wits end here. You can email me at [email protected]

well, there is no refrence voltage. the o2 sensors that saturns use generate voltage in the presence of oxygen. the range is from 0-1volt. i cant tell you why its not working. you could have a rich or lean condition which is causing the sensor to have little activity.