About last month my ses light went on nd I got it scanned. Results were p0138 + p0036. Bank 1 center 2. Doing some research nd came up with them being the o2 sensors. My 04 mcs has 118k nd the previous/original owner didn't really take much care of the car. I just got an alta car back exhaust put on. Just wanted to make sure that those codes were for both o2 sensors nd nothing else? Would the alta exhaust make a difference? After the exhaust was installed I felt a hella loss of power. Very sluggish nd I have to really press the throttle for it not to stall out in first. Also, my fuel economy is a joke. Would this be both o2 sensors? Help!

 

Bank 1 sensor 2 is the O2 sensor after the catalytic converter. It sounds like something was not completed correctly. You should not have a loss of power after changing the exhaust.

Perhaps you have a leak in the exhaust. Take it back to the shop or another shop for an inspection.