I think alot of the keys have become obsolete because of software changes. 2A, 5A, 7 12A, 13, 17, 20, 24 and 25 seem to be the only keys I ever use. some oddball cars that I rarely see may use the others. in addition I have 9, 13A, 14, 15, 16, 18, 21, 22. I th... Login to read more.