Which of the following sentences is correct and why:
It'll perform checks on itself
It'll perform checks in itself
I'm writing about a computer system that is going to perform checks in order to make sure it's not being modified.
The first sentence is correct; the second is incorrect. This is because 'check (up)' can be used with 'on' preceding an object (not 'in' or 'at' or another preposition).
E.g. I'll check (up) on you tomorrow = I'll see how you're doing.