This post is WRONG!----->(((bank 1 refers to the driver side cylinder and bank 2 for the passenger side, if the error is bank 1 sensor 1 that is the sensor on the driver side pre cat converter. bank 1 sensor 2 would be the post cat. bank 2 would be the right side and so on.))) SORRY!
if ever there are more sensors then that will be bank 1 sensor 3 and so on
But this part is CORRECT ----->> black connectors wont fit into gray connectors
tags: PO155, PO161, Heater Circuit Malfunction