DO not know what Position one is but do know where the senors are. there are two kinds and yes they have been mandated for some years now.. (You ask who knew.. I for one and many others here as well)
Some vehicles use teh ABS sensors and assume if one wheel is consistantly spinning faster than the other the tire on that wheel is "Smaller" WHich means under inflated.
The others use actual pressure senders in the rim.. You remove the tire. remove the sensor replace the sensor. re-mount and re-blance if necesaary and job done.