. . .Oxygen sensor on 92' Buick LeSabre

Where is the oxygen-sensor on my car, why do I need one, and can they be repaired or replaced? Any help with this one fellas- would be much appreciated. . . . It’s a 92’ Buick LeSabre Custom

It should be located on the exhaust header pipe ahead of the catalytic converter, the ECM (computer) relies on the signal generated by the O2 as a means of controlling the air/fuel mix, and they can be replaced. There is no repair to be made on them.

O2 sensors are often misdiagnosed. What are the symptoms, etc that lead you to believe the O2 is bad?

Where’s the ‘exhaust header pipe ??’ Dum, Har. (I guess I wouldn’t know it if I was staring right at it). Are they expensive? Or difficult to replace, when having a shop replace one? My engine sounds really rough all of sudden. . . .