P0012 code vvt solenoid location

Need help locating the two vvt solenoids. I have had a problem with a knocking noise after long distance driving. It's not real bad and dosent last long, I finally had a check engine light come on and came up with the error code p0012 retard cam position and they were telling me that it was one of the vvt solenoids. Does anyone know where this is located, will it make your engine knock a little on rare occasions, is it an easy fix?
This is on a 2011 Tacoma 4.0 with 180,000 miles.

 

There are a couple of threads on here with pictures that will help.

 

https://www.tacomaworld.com/threads/vvt-replacement.685602/unread

Look through this thread

 

This should help:

Here:





The filter plug will look like a bolt drain plug: