O2 Sensor Values - What is "Normal"?

[TimGFL]

Greetings! General question about O2 sensors voltage here.

I picked up a bluetooth doohickey and Torque app, and I noticed that on my 1996 3.4 automatic, my O2 Bank 1 Sensor 1 is reading between .3V and .8V. If I understand right from digging through the T4R forums, that is pretty much normal operation and it should cycle right around .5V in the middle.

However, my Bank 1 Sensor 2 is reading between .0V and .1V. Is that normal?

Also, I presume that Sensor 1 is upstream and Sensor 2 is downstream, correct?

My STFT is showing it's running at about +5-6%, which if I understand right is just a little higher than "ideal"

I'm not getting any O2 sensor codes, but I do have a P0505 code and performance issues I'm trying to troubleshoot as well in a different thread, so I'm wondering if the O2 sensors may be related (since I've ruled out the IAC, MAF, TPS, ECT, plugs, wires, and vacuum leaks).

Thanks for any feedback you can offer!

 

[spartacus]

Greetings! General question about O2 sensors voltage here.

I picked up a bluetooth doohickey and Torque app, and I noticed that on my 1996 3.4 automatic, my O2 Bank 1 Sensor 1 is reading between .3V and .8V. If I understand right from digging through the T4R forums, that is pretty much normal operation and it should cycle right around .5V in the middle.

However, my Bank 1 Sensor 2 is reading between .0V and .1V. Is that normal?

Also, I presume that Sensor 1 is upstream and Sensor 2 is downstream, correct?

My STFT is showing it's running at about +5-6%, which if I understand right is just a little higher than "ideal"

I'm not getting any O2 sensor codes, but I do have a P0505 code and performance issues I'm trying to troubleshoot as well in a different thread, so I'm wondering if the O2 sensors may be related (since I've ruled out the IAC, MAF, TPS, ECT, plugs, wires, and vacuum leaks).

Thanks for any feedback you can offer!

Sensor one, up stream should cycle like it is. Sensor 2 down stream does not cycle because it only monitors the efficiency of the cat and has no effect on fuel control. Engine should be at operating temp and not in closed loop. punch the gas and see if the the O2 sensor bank 1 sensor 1 cycles quickly between 0.1V and 0.9V.

 

[gamefreakgc]

Normal operation, all is well. If you are cruising on a flat stretch of road and it's safe to look, check out the Bank 1 Sensor 2 signal. More often than not it will also cycle up and down similar to the front, although less pronounced. It has a very small impact on fuel trims, much less than the front O2 sensor.

Any fuel trim +/- 10% is considered within normal range. A fuel trim +/- 39% indicates an issue. I believe once it hits +/- 40% it throws a check engine light.