bank 2 is the drivers side of the engine and sensor 1 is in the exhaust system ( either the exhaust manifold or the EXHAUST PIPE before the exhaust enters the catalytic converter )

what is bad exhaust system?

Exhaust system brackets are used to hold the exhaust system in place

All O2 sensors are threaded into the exhaust system at various points. Bank 1 Sensor 1 would be the first O2 sensor located in the exhaust system after the bank of cylinders that contain the #1 cylinder.

The exhaust valves are the hottest component of the exhaust system of an internal combustion engine.