SO my 2007 baselne sky has been throwing a bunch of codes for the past few months. Most have been for Catalytic converter issues. I have already changed out the downstream o2 sensor which actually did turn out to be faulty. I have also done a pressure test and found that I am not leaking pressure anywhere in the hoses. Checked the back pressure on the front side of the cat itself and there doesnt seem to be any building so the cat is not clogged. But im getting error code P0420 so my last option is to change out the upstream sensor now, which based on the diagnostic readings it is fluctuating more than it should. Does anyone know the OEM part number for an o7 sky for the bank 1 sensor 1?