Chrysler Repair: O2 sensor: remove and replace, vacuum line, box end wrench

Question
87 lebaron 2.5L L4 FI OHV 8V showed power loss until I found a disconnected EGR vacuum line. Now the only trouble code is a 51 . Is this the O2 sensor? If so how difficult is it to get out. i have sprayed the sensor with loosening stuff. Does the manifold need to be hot to remove it? What do you think is the best way to go?  

Answer
Hi Herman,
It may be that the code 51 is left over from the egr problem unless you already erased the fault codes and the 51 is a new one. Disconnect the - post cable from the battery for a few minutes to erase previous codes and then check after a few trips to see if the 51 comes back (you will get a 12 code due to disconnecting the battery but ignore that). If you get the 51 code then as you have done, spray penetrating oil on the shell threads and let it sit overnight. It may be easier to remove if the engine has been warmed up, but be very careful not to burn yourself. Use a 22mm box-end wrench for removal. Twist the sensor back and forth to loosen the threads gradually. If you can find an 18mm x 1.5 x 6E tap you might then clean the threads of the manifold. Be sure new sensor has anti-seize compound on its threads. Tighten to 20 foot-pounds being careful not to damage the wires (that is about the same torque as for a spark plug).