checking your code po156=ho2s sensor circuit malfunction (ho2s-22 meaning downstream o2 and pcm connector pin 61). recheck the sensors or for exhaust leaks since our engine is mounted sideways what side is front of engine? your downstream sensor affected is on engine side opposite of cylinder 1 side. cylinder, upstream02(ho2s-21), precat, downstream 02. this is as much info as i can piece together for u