Hyundai 2005 Sonata Owner's Manual page 144

!
CAUTION:
o Do not clean the inner side of the rear
window glass with an abrasive type of
glass cleaner or use a scraper to remove
foreign deposits from the inner surface
of the glass as this may cause damage to
the antenna elements.
o Avoid adding metallic coatings to the
rear window glass, such as Ni, Cd, etc.
These can disturb receiving AM and FM
broadcast signals.
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FEATURES OF YOUR HYUNDAI
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