WHICH O2 SENSOR HAS THE

Hi.
The Oxigen sensor are in diferent kind.
1 -- With a single wire. " is only oxigen sensor"
2 -- With 2 wires " is only oxigen sensor"
3 -- With 3 wires " Is oxigen and heater sensor"
4 -- With 4 wires " is oxigen sensor and heater sensor.
5 -- with 6 wires " is oxigen, heater A/F sensor" normally Nissan)

OK........Your question.
Depend of the year of your car.
But all the car they are Bank 1 or single bank. Engine in line
4 cyl . or 6 cyl. And are identified sensor 1 bank 1 and sensor 2 bank 1. S11 or S21.
But all the Engines in V are bank 1 and bank 2.
Sensor 1 bank 1, sensor 2 bank 1, S11 or S21.
Sensor 1 bank 2, sensor 2 bank 2, S12 or S22.
Sensor one is alway before catalystic.
Sensor two is alway after catalystic.

If you have problen with the oxigen sensor you need to put a scanner to see the number of code, The number of code will give the especific sensor that you need to replace.
The code can be heater or oxigen. and can be refer to a the same sensor.

I hope this information work for youu.
Thank you for use fixya.