Bank 1 means left side of engine usually on a V-6 or perhaps can mean left side of exhaust on a dual exhaust car...not sure how this relates to your 4 cylinder engine. Where are you getting this description?
In any event, it might not be relevant, which is why you can't get a straight answer. It may not pertain to your 4 cylinder car.
The secondary sensor, sensor 2, is located on your catalytic converter. It would be the sensor furthest downstream.
it's not the one that says A/F sensor, it's the one further back in the diagram that also looks like a spark plug in the drawing. Sorry but our website cuts off the label to it.