Talk:Sans/@comment-28484772-20160517190629/@comment-26347196-20160517191035

If I were to think about it, most of the time, Sans teleports to places where you can currently access.

Given the doors to the Ruins never opened (and as you exit the Ruins, you can't return until after Asriel battle), and that Sans never teleport to the ruins, I'm thinking he can't travel through walls.