P0420 Help please.

[Cw370TT]

So I've got the p0420 Cat effic. Below normal bank 1. Hooked it up to the scanner and decided to check the o2'status. Bank 1 AND 2 o2 sensors position 1 AND 2 will not read. In case I didn't say that right the o2 sensors at the rear on both sides will not rwad. The ones in the front will read and fluctuate. The 2 rears on both sides read 0 with zero fluctuation. What's going on here? Is it Cats? O2 sensors. Or something electrical idk. Thanks for any insight!

Oh and at the moment I can't search the forums on my phone. I can do google but mostly all I find is replace a cat but in my case looking at 2 sensors that won't read on both banks. These are position 2!