For troubleshooting the 02 sensor on my 2011 E150 4.6L, my manual says to measure the voltage between VPWR and SIGRTN. But my diagram of the harness only shows the following connections so what is the SIGRTN?

U02SPCT
U02SPC
VPWR
U02SGREF
U02S
U02SHTR

 

Signal return is usually the wire that brings the O2 signal to the computer.
I don't know what kind of manual you have , but it is anything but clear.
I would suspect the sig Ret could be UO2S as the sig wire and GREF is the ground.

 

Which O2 sensor is in question? Bank 1 or 2, first or second sensor.

 

I'm testing the first sensor on bank 1 and 2.

 

OK here is the wiring diagram for the front O2 sensors and connector view. Obviously VPWR is pin 4, I think signal return would be pin 3, I could be wrong though.

 

Thanks!