Knocking sensor on 1.8t AUM conversion

Hey Guys,
Just a few snagging issues on my conversion.
I was a complete newbie with my build so I'm learning as I go along.
I'm running emerald management but as I was checking over the engine bay today I found the knocking sensor wedged in between some pipes!
1, can anyone tell me where it goes
2, do I need it and where am I wiring it to?

Just a little confused.
Any help would be great.

Thanks.