I have a '97 Ranger 4.0 and keep getting code "PO141" which says I have a heater malfunction in my O2 sensor (Bk 1 Sensor 2). I've replaced the sensor with a new Motorcraft one and get the same code. Can anyone help me with this?
Tks

 

That's not a malfunction. It's telling you it's too lean. You may have the vacuum leak between the upper to lower intake or a line somewhere. Or even a dirty MAF can give you lean codes.

 

97 where known for the lower intake gaskets leaking i had lean codes till i replaced them