It would be the sensor after the catalytic converter.
bank 1 should be the left exhaust manifold.
A B1S1 O2 sensor would be threaded into the exhaust system between the catalytic converter and the engine.
where is the oxygen sensor in a 1995 gmc jimmy
one on each cylinder bank and then before and after the cat converter. there all on the exhaust.
Bank one sensor one is above the converter.
This would be the sensor after the catalytic converter.
It is behind the catalytic converter
Bank 1 is the oxygen sensor either screwed into ,or above the catalytic converter. Bank 2 is below the catalytic converter.
Bank 1 sensor 3 would be the O2 sensor after the catalytic converter.
driver side bank 1 before cat
Bank 2 is on the passenger side on a Chevy V6 or V8.
Bank one is the side of the engine with cylinder #1. Sensor 2 is after the catalytic converter.