How many oxygen sensors are there and where are they located on a Chevy S-10 4.3L?

Answer 1

Check if the vehicle is OBD-1, or OBD-2. If it's OBD-1, there will be 2 Oxygen sensors, one in front of the catalytic converter, and one at the rear of it. If it is OBD-2, there will be four sensors. There will be three on the "Y" pipe from the manifolds, and one before and after the cat.