What is this part? (related to P0021)

[Daytona]

Hey all,

 

New member here, just spent my hard earnt money on a 2007 Legacy 3.0R. Really great car and has been going awesome until a couple days ago when the following happened:

 

- Was driving normally then check engine light came on

- Was probably doing about 3 or 4k RPM was not driving hard

- Cruise control and sports mode selector also was flashing

- Bought a diagnostic scanner and found the code to be P0021

 

Other notable things:

- Car has done about 103,000km

- Oil has been changed at 100k

 

Oil does seem to be leaking from the thread on that, check out below pictures. This is a 6 cylinder engine. It's not a fast leak, it's seeping slowly. Although when the check engine light came on and I got home (was only about 2km drive), I'd say I had to fill up at least 500ml of oil.

 

Now I've located the AVCS solenoid and will be taking it out for a clean, but my bigger question is, what is the screw that you undo with an allen/hex key?

 

I can't seem to find any posts that talk about that screw and what it's for, I'm guessing it controls oil flow/pressure.

This is on drivers side, passengers side seems fine.

 

EDIT:

I have found this post:

http://legacygt.com/forums/showpost.php?p=1943328&postcount=8

 

And that's really useful, but that seems to be off a 4 cylinder engine and if it's got a hex nut, it seems to be obstructed.

[Daytona]

A bit of a bump on the thread just to see if anyone knows what that hex nut is for.

I ended up taking all the solenoids out and giving them a spray down with WD40, no error code since.

 

But if anyone know's what this screw is for, would be really appreciated!