After replacing the transmission on my 2004 Ranger 4.0 4x4 I cannot locate the engine side connectors for the upstream O2 sensors. There is one in the wiring harness over the top of the transmission but I don't remember which side plugs into it. I cannot find the other connection.

 

Welcome to the forum

Hope its not inside the bell housing, that happens when transmissions are removed and replaced, feel around the upper bell housing where it meets the block

There are 4 wires on the O2 sensor plug, Red/white wire is passenger side, Yellow/light blue is drivers side
Check the wire color on the one you found, then you will know the area to look for the one you can't find

 

Yeah I hope it’s not in the bell housing at least I know where to look. Thank you