In article , Jeff writes:

Are you in GPS or NAV mode?
GPS - the CDI would be reading the GPS course
NAV - it would be reading what you had your OBS set to and your NAV receiver
set to
the freq of the navaid
what GPS/ NAV do you have, the garmin 430 and the NAV that you can get with
it?

I know that when I am having my auto pilot track a VOR it may be off by a dot
sometimes, this is basically because the VOR is not that sensitive when your
a ways
from it. But when I shoot a localizer, the AP tracks it perfect. Have you
tried
tracking a localizer with your AP ?

When I am flying a GPS course (with the garmin 430) straight and narrow, the
CDI is constantly about one dot to the left. Same for an ILS, though the
Garmin goes into approach mode and the full scale CDI is 0.2 nm. Thus the
"error" is only a couple hundred feet. I generally fly the last part of the
approach so, no problem at all.

I've decided to take the advice of several and leave it alone and say that it
is the nature of the beast. Thanks to all for the comments.

Chuck