Dodge 2008 RT Caravan - Manual (Page 249)

Compass Variance
Compass Variance is the difference between magnetic
North and Geographic North. In some areas of the
country, the difference between magnetic and geographic
North is great enough to cause the compass to give false
readings. For the most accurate compass performance,
the compass variance must be set using the following
procedure:
NOTE: Magnetic materials should be kept away from
the top of the instrument panel. This is where the
compass sensor is located.
UNDERSTANDING YOUR INSTRUMENT PANEL 247
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