I live rent a room from my cousin he is on probation. Can his p.o. come and search my room if I have my door locked.
The house is not in his name its in his moms name so he rent from her and I rent a room from him type thing.

Does not matter whose name the house is in, or whose room. He already signed a "blank search warrant" consent when he got on probation. The thing here is that he could secrete illegal items in YOUR room even ifyou are not aware of these items. Hence the PO can legally search the entire house, locked rooms included. He can also open closets, root through dresser drawers and locked luggage, etc. As long as it is at the residence of the person on probation EVERYTHING is game for the PO if he so choses to look, search, etc.

If you have nothing to hide, then you should not be worried. If you do have something that would get your cousin in trouble, then get rid of it. Weapons of any kind are illegal, so if you have a gun then by all means keep it off the property. Same goes for very large hunting knives.