Looking at the vehicle from the front on all rear wheel drive engines the passenger side is bank 1 and the drivers side is bank 2 if you have front wheel drive your engine is just turned to the right so bank 1 is closest to the windshield and bank 2 is closest to the front grill now you know what the banks are and sensor 1 is the first sensor on that side and sensor 2 is the second sensor on that exhaust line and this is the same for all ,so your answer is plain to see now