I have 3 front and 2 rear sensors on my BMW M6. I have had the warning F1 sensors is not functioning when I start up the car for a while now. I am having the front bumper pulled this coming week so it's a perfect time to swap out the bad sensor with a new sensor. I have the new sensor in hand. My question is what sensor would F1 be? Is this front driver side or front passenger side? I am sure there is a logic to where F1, F2, F3 is located but I just don't know where F1 is. Any help would be super appreciated!

Brian