90SR5-4runner

I have searched the forums and have not been able to find a good solid answer to help me. I probably missed it so I'm asking for help. I have an 03 Tacoma with a p0136. Plugged in my OBDII and pulled my live data. I have 2.185-3.145 on my 1/1 sensor and .020-.030 on my 1/2 sensor. I believe the 1/1 sensor (pre-cat) should fluctuate from around .100 to .900 in accordance with A/F adjustments by the ECU.If I am correct than I have a problem here with my readings for the 1/1 sensor, can someone affirm my beliefs or correct me please. I don't understand why I do not have a sensor 1/1 code if the readings are bad...... and on the sensor 1/2 side of the matter, I am thinking it may be Lazy, but I am hesitant to start replacing sensors, I would really like to troubleshoot this a little better, Can anyone help me? Thank you so much in advance.

98_3RZ

you're looking at it KINDA wrong, o2 sensors do work on a 0 volt to 1 volt scale, BUT because your tacoma is a 2001 and newer, sensor 1 (pre-cat) is not an o2 sensor, it is an air/fuel ratio sensor, so it works on a different voltage scale (can't remember what the scale is exactly, but your readings in the 2 to 3 volt range are where they're supposed to be), sensor 2 (post-cat) is still an o2 sensor, and the code description is oxygen sensor circuit malfunction bank 1 sensor 2. replace your passenger side o2 sensor and go from there