crankshaft postion sensor

I need to replace the crankshaft position sensor but my problem is I do not know where it is located. Could someone please tell me where it is located?
Thanks

I need to replace the crankshaft position sensor but my problem is I do not know where it is located. Could someone please tell me where it is located?
Thanks
New guy, here to. Are you having starting problems. What year, model,engine type.