You don't say what vehicle :( but Bank 1 is the one where cylinder 1 is.
For an non-transverse engine, it's the bank on the passenger side of
the vehicle. Sensor 2 would be the one downstream in the exhaust
(towards the rear for a non-transverse engine.
It's telling you that that O2 sensor has high voltage - probably bad
sensor, or might be problem in the cable to the sensor.
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