d16z6 vtec head, shot?

ok, so I took the valve cover off of my engine to find this, I don't know what it is or if it is vital. It is a plate with what looks like little sensors on it that read where the lobes are on the cam, they move up and down, there is something like 6-8 bolts holding this plate down, well problem is is that it is cracked in the middle, and has some play in it. any ideas what this is and if it is really needed. thanks, I know it kind of vague, but its the best I can do at 4:17 a.m.