Waiting for my actron OBD2 scanner to come in to see all what codes im throwing after my b18b in cx hatch swap.

For my o2 sensors, when I removed them I didnt remember which one went before the cat and which went after the cat. Does it matter which goes where? I know what plug is for which sensor, but dont remember which sensor goes where.

Also the sensors from my cx will work with my b18 motor and ECU right?