How do to tell which 02 sensor heater is needed

Question

my mechanic told me I need to replace my 02 sensor heater circuit fault b2S2, Code:PO161

Answer 1

P0161 H02S heater circuit Bank 2 Sensor 2

This would be true, In order for the 02 sensor to work properly it needs to maintain a proper heat level, this is what the heater circuit does the fix for this is with the 02 sensor .