Which sensor is bank 1 sensor 3 on 2000 Chevy s10 with 4.3?
That should be the sensor located after the catalytic converter.
Bank 1 is the drivers side of the engine and bank 2 is the other side. Sensor 1 will be the first sensor that's screewed into the exhaust pipe where it bolts to the exhaust manifold. sensor 2 will be further down the exhaust pipe towards the converter. There are 2 in the pipes on each side of the engine.