Code 12 is a GM code which means that the computer has not detected any problems with any of its sensors or other computer components. In other words its the "All Clear" as far as your computer system is concerned. Are you having a problem with the vehicle?
December, 15, 2012 AT 4:11 PM
Code 12 is no distributor reference form the distributor. In other words, the motor is not running. Normal for key on, engine off check for codes. Its the other codes beyond that we need.
If you have a code 12 with it running, there is an issue with the distributor itself.
December, 15, 2012 AT 7:18 PM
Watch this video and it wilmay clear things up for you.