I have 96 Caravan 3.3 with 180K miles. I'm getting check engine/service engine light. I have a OBD2 code reader and said O2 sensor circuit no activity detected at bank 1 sensor 2. What does it mean by bank 1 sensor 2. I think there's two O2 sensors. One before the Cat and one after the Cat. Which one is bank1, bank2 and sensor1, sensor2?

 

Bank 1 is always the engine bank with the #1 cylinder. For example if the #1 cylinder is on the left side of the engine that is bank 1. Sensor 1 is upstream of the cat and sensor 2 is downstream the cat. In this case there is only 1 downsteam sensor, so that will be bank 1 sensor 2.