1997 ford f250 v8 with 4 o2 sensors. Got check engine a couple days ago, and code reader says P0-0141, Heater circuit malfunction bank 1 sensor 2. driver side downstream of cat. Picked up a new o2 sensor on line, tried to get the old one out but it was frozen in to the pipe, so I thought I would check out the old one for the heck of it before I went to setup torch etc.


I disconnected the wire harness and checked the 2 posts in the connector, 4 ohms, the new one read 6 so it looked like the heater circuit was ok in the old sensor. I then checked with the key on the voltage coming from the connector that comes to the o2 sensor and it read + 12.5 v in relation to the ground of the truck body. My meter read 2volts in relation to the 2nd pin in the connector, sometimes 1 volt It seems to me that the problem lies somewhere between the ecm and the connector that goes to the 02 sensor,


When the ecm gives the signal to activate the heater by completing the circuit to ground, is it completely on showing 12v or can it be partially on showing something less?


There seems to be no fried wires between the ecm and the end of the connector, and no other error codes


I cant find a good wiring diagram.


What do you think???
Help Please

 

The code is for an open or high resistance pass side rear sensor..
Measure the heater resistance on the other sensor to compare.
The original sensor at 4 ohms will draw about 3 amps. That is 12 volts divided by 4 ohms = 3 amps.
The 6 ohm sensor will draw 2 amps, a 33% difference.
The PCM monitors both voltage and current so the failure could be either or both to much current, harness or a poor ground.
Do not measure resistance of the sensor portion because the meter applies voltage that could damage the element.
Good luck.