i drive a S-10, 1997, 2.2 liter, long bed

my SES light comes on pretty much every other couple of days, sometimes for all day, sometimes for only a couple hours.
i got it checked out as a p0405 code =

which says: EGR Flow - Sensor A - Circuit Low Input

anyone have beta on this??
where is the EGR valve under the hood.
my haynes manual says its located "on the backside of the cylinder head under the hood cowl"
im having difficulty locating it. also the manual does not describe any isolated sensors that monitor the EGR valve.

now, my theory is that since it's a sensor A, circuit low input, this indicates its only an electrical issue, and not a mechanical EGR issue which would signal another code,
probably related to "EGR Flow - flow in excess" or "EGR Flow - flow insufficient", etc, etc. so im reluctant to just change out the valve (expensive).
since the light does not flicker, i dont think the wire is being shorted out, but because it has a long-term flicker as described above, i feel something in the mechanics of the EGR may be self regulating and sometimes can't regulate hence the SES light coming on when it does.......

but really, i have no idea
thanks
-jordan