Mazda 2012 CX-9 Owner's Manual page 277

Interior Comfort
Audio System
Message display
If CHECK CD is displayed, it means
that there is some CD malfunction. Check
the CD for damage, dirt, or smudges, and
then properly reinsert. If the message
appears again, take the unit to an
Authorized Mazda Dealer for service.
qOperating the Auxiliary jack
You can connect portable audio units or
similar products on the market to the
auxiliary jack to listen to music or audio
over the vehicle's speakers, refer to
Auxiliary Input (page 6-66).
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