o2 Sensor problems....

96XJ~ 4.0 ~ AW4 tranny...
Tranny goes out so got it replaced. Check Engine light comes on when the tranny went out. Checked the codes and it was for a bad downstream o2 sensor. Replaced the sensor with a new one and had the codes cleared. Drove it for two days and the check engine light comes back on...same code. Replace the sensor again with another new one, cleared codes and drive it for a couple of days and you guessed it, the check engine light comes back on and yes, it is reading the same code, "High Voltage o2 Sensor"....

Could anyone tell me what the heck is going on here??? Please???
Thanks in advance!

Wire on exhaust?? maybe getting pinched somewhere??

I checked for wires on the exhaust and nothing there. I will trace the wires to see if a malfunction is somewhere in their path....
Thanks....

Ok, no bad wires but I did find a small leak in the fuel return line going back to the tank. I know that the fuel pressure will effect the running/starting etc. but could low fuel pressure caused by the leak effect the o2 sensor to the point that it kicks a code?