how do you know which o2 sensor need to be replace in bank 1 up stream.

Question

theres 4 o2 sensor 2 up 2 down how do you khow which one

Answer 1

P0131 - 02 sensor circuit low voltage (bank1 sensor1)

When it comes to the term "bank" the definition mean arranged in a row. Bank 1 is reffered to where cylinder number 1 is located and bank 2 is refered to as where cylinder number 2 is located at, Upstream or down stream are reffered to as flow, which is how the flow goes , Exhaust created by engine combustion start at at stream then moves the outside by the way of downstream Upstream 02 sensor are engine management sensor and down stream are catalytic monitor,