Mazda 2012 CX-9 Owner's Manual page 278

Interior Comfort
Audio System
qError Indications
If you see an error indication on the display, find the cause in the chart. If you cannot clear
the error indication, take the vehicle to an Authorized Mazda Dealer.
Indication
CHECK CD
6-36
Cause
CD is inserted upside down
CD is defective
Insert the CD properly. If the error indication continues
to display, consult an Authorized Mazda Dealer.
Insert another CD properly. If the error indication
continues to display, consult an Authorized Mazda
Dealer.
Solution