I got the same codes off my ECU (knock and EGRC solenoid valve).  I
replaced the EGRC solenoid valve but my check engine light came back
with the same exact codes.  I don't know what my next step should be.

When you changed your EGRC solenoid valve, did you notice that there is
another solenoid valve next to it that is a different color.  The
replacement part that I got was black so I naturally swapped out the
black one mounted in my car but I noticed an almost identical valve
that was red in color and mounted upside down fro the orientation of
the black one.  I'm assuming I did this correctly as I consulted the
Hayne's Manual too.

Any help would be appreciated.