Hiya,

Bank 2 O2 sensor when fault present and open loop and lumpy, im sure it stayed at 4.6v, but i'll check my notes again. You mentioned "0.45v to 0.495v", i think you are refering to the wrong type of sensor there, 0-5v is the range of these, not 0-1v.

I agree, gas readings do indicate a lean mixture causing a misfire, and its only on those 3 rear cylinders, and it cant be narrowed down to 1 cylinder. Again i will check my notes on the amount of drift.

As the engine reaches operating temp, both sensors go closed loop, but only bank 1 sensor switches, it takes a few minutes for the ECU to register the fault and indicate an open loop state on bank 2.

"Any codes stored???" A clue is in this posting title, code 203 - O2 sensor cyl 4,5,6 range/performance.