Your Mazda radio comes with an antitheft feature that makes the radio inoperable when the car's battery is disconnected or when the radio is removed. Fortunately, you can easily unlock your Mazda's radio with the proper code. If you have lost the unlock code, you can contact the manufacturer for the information or find it yourself.
Consult your Mazda user manual. It should have the serial number and unlock code near the front or back of the manual. If you have only the serial number, call the radio manufacturer.
Provide the serial number. This verifies that you are the owner of the vehicle and radio. Write down the unlock code.
Insert the key in the ignition. Turn it to power on your car. Wait for the radio to display "Locked" or "Code." If your vehicle was made before 2004, it will say "Locked." If it was made after 2004, it will say "Code," according to I-Car Advantage Online.
Press and hold the tuner button. Enter the unlock code, using the numerical keypad. Repeat this step until you have entered all of the numbers. Press the "Set" button. Your radio will automatically unlock.
Never leave your unlock code in an open area. Entering the unlock code incorrectly three times permanently locks your radio. In this case, take it to your car dealership to remove the lock.