O2 Sensor Problmes

[Nabromovich]

So my 2000 Sierra 2500 6.0 4x4 started giving me an intermittent Serivce Engine light, so after looking at the code it was P0157 (low voltage to Bank 2 sensor 2) So I repalced that sensor today and cleared all codes, about 30 mins later the light came back on with the following: P0157 (same as before) and now with code P1153 (not right amount of switching from lean to rich) Help me please. Keep in mind that I wasn't getting P1153 before I replaced Bank 2 Sensor 2....Odd to me, maybe the whole wiring in bad?? I don't know what do you guys think?

[FargoZ71]

Clogged cat? Smell bad out the back? Most likely is something between bank two / sensor 1, and bank 2 sensor 2.. leaves the cat.

I just had to replace Bank2/ sensor 1 today cause it was missing and giving my p0151 and p0300 and one other code.