Repeat O2 Sensor code

Ive read some threads on here about other peoples similar or exact issues with repeat O2 sensor codes. I have a 2010 4 cyl access cab that threw a code for my down stream sensor, i work in a shop so i scanned it, came back Bank 1 Sensor 2 low circuit code P0037 if i remember correctly, Ive replaced the downstream multiple times as thats the only code i get, added a adapter to pull the sensor out of the exhaust a little a friend said might help, replaced the cats, and tried replacing upstream for the hell of it. Threw the same one and only code every time. My next step is gonna be checking my fuses. Other than that i have no idea what to do, dont want to take it to toyota to diagnose and screw me with a huge bill, but this CEL with no traction control sucks. I feel like ive noticed a small dip in MPG also but cant say for sure. If anyone has any other suggestions if you or someone you know been in the same boat, Thanks in advance

 

That code is for the O2 heater control circuit being open, you need to check the heater circuit.

Pin 2 (Blue/White) at the O2 sensor should have battery voltage with the key on.
The PCM grounds Pin 1 (Green) when the O2 heater is commanded on, you can use a scan tool with bidirectional control to turn it on.
If you put a test light across pins 1 and 2 of the O2 connector and command the heater on it should light up.

 

This. My 2.7 was throwing the code and it was one of the wires leading up to the sensor, not the sensor itself. It was intermittent because sometimes the broken wire would touch, and sometimes not.

 

Sorry In advance, would that be in the fuse box under the hood? I’m not sure if my scanner has the bidirectional thing, we have a test light and volt meter here but not exactly sure how much that will tell me. I’m currently looking over my wires before the sensor plug in to see if it is that

 

for my fuse box diagram, I have a 15A “A/F heater” fuse I’m not sure step by step how I should go about this, not sure if the scanner we have has the bidirectional capability

 

In my case, it was actually the harness under the car about 3 inches from the sensor.