Agree...it could be a bunch of different things that will throw that code. I had tested the 12v when i would get the error and it would label my battery as bad and to replace. What I also figured could have been a part of it was any 12v accessories I was using within the car adding additional drain. If you are using your car and dont have any additional accessories (dashcam, phones, etc) then its probably something else. If you do have anything connected regularly while driving (same items or more as above) I would also recommend as a test to swap out the cables you are using with better quality ones and or use a different USB port to test. This is how I diagnosed my issue and how I could determine the 12v tested good one day, bad the next, and then good again. There definitely was something (accessory or other) that was causing additional drain on my battery. So replaced the cables and battery and so far so good.
2016 Magnetic FFE - Canada