Poor gas milage, 1995 Buick Regal w/super charger .I was told it could be oxygen sensor. Where is it located?

Screwed into the exhaust pipe coming off the exhaust manifold before it reaches the catalytic converter. That is the downstream sensor (usually goes first) There is an upstream O2 sensor also, I believe it is screwed into the air pump cannister? Need to research that further, would need your specific engine details. Mike

The o2 sensors are in exhaust pipe under car. start at front and work towards back. you will see them screwed into exhaust pipe. have a good day !!