Something similar like this happened to me when I put my headers on also. Actually looking for the answer why is what brought me here. I ended up changing an O2 sensor and it fixed it. Someone told me that the headers might have had something inside the tubes to ruin the sensor. which sounds plausible, but you never know. just try checking the voltage in them to see if they are all consistent. And yes, I believe bank 2 is passenger side. the code should say like bank 2 sensor 1 or something like that.