2006 RAV4 w/ V6 engine. Had a P0158 code, and replaced the bank 2 sensor 2 with OE Denso. Was fine for a few days, then got the same code. Reset it, and it was OK for a few days again, but got he same code again. It seems to occur at highway speeds, rather than in town driving. There are no additional codes. I ran a bottle of injector cleaner through the system, but no change. It seems that the sensor is working properly, but there is another issue. Am I correct in understanding that P0158 would be a high voltage, related to the mixture being rich? Any thought as to what might be causing this problem?