It depends on your school. 3 is considered passing grade by the collegeboard, but some schools only accept 4+. For example UCI [0] allows 3 for credit, but USC [1] only accepts 4 or above, which I guess is progress since in high school one of the factors (besides the price) was that USC wouldn't accept any AP credits at all.
Just a nitpick: as others have mentioned, the College Board has no concept of a "passing" grade. Just numeric 1-5. It is colleges and teachers that consider a 3 or better "passing".