I had this problem many times when I first got my 2005 Cobalt in 2005. The tech's would reset it somehow but it would always happen again and sometimes become "unclocked" on it's own. Eventually the whole radio/CD player was replaced under and it has not happened again. So it seems like you may need to head to the dealership. Sorry!
~MW
2008 Chevy cobalt tpms reset
My fuel gauge, odometer and radiator gauge isn't working and my radio says locked. How can I fix this?
There is no fuel reset switch on any model cobalt if i remember u can do that by disconnecting the battery for a couple of minutes.. that will reset the computer
Chevrolet does not use inertia/reset switches.
I've only gotten that icon once. i attached a amp to the front speakers, causing signal interruption(more like Chevy mixing up wiring diagrams) and locking the stereo and the dash... icon just means your radio isn't giving the right signals or you jacked another radio from another cobalt. each stereo head is set for that car only. dealers can reset the stereo head unit to match.
Scan tool
Contact the dealership. Most can obtain a unlock code for the factory radio. Since it's a Chevy I'm assuming it's a Delco raido. Go to www.delcolockcodes.com and they'll be able to get you your specific unlock code.
drive it into a lake
I had a problem before with my 1998 firebird where the radio locked and I had to get a code to unlock it now it is locked again and I don't have the manual to get the instructions to unlock it but I do still have the code.
Fix the cause of the light coming on and the light will reset itself within a few drive cycles.
You insert the code with the radio presets. Just push the reset # that corresponds to the radio preset. If you have locked the radio up just leave it on for a few hours and it will reset so you can enter the code again.
Unhook the car battery.