How do I reset my Kenwood car stereo?
What does it mean when your stereo says protect?
If there has been an electrical surge or power outage, then the internal surge protection inside the home audio device may have been triggered to protect the device from the surge.
How do I unlock my Kenwood car stereo?
The workaround is to enter the wrong security code. In models with this bug, decrement the third character of the security code by one. For example, if the security code is 1111, enter it as 1101. If the security code is 9999, enter 9989.