the O2 sensors are located before and after the primary catalytic converters. I don't know if bank 2 is the driver's or passengers side but I do think SENSOR 2 is the on after the convertor. A MAF sensor malfunction will trigger that error code. I found out the hard way. I replaced the sensor the error code suggested, cleared the error code and it kept coming up. replaced the MAF and the error code disappeared. kind of a toss up.