In order to enter a code, it is required that you collect all Enigma Code Collectibles in the game that are necessary for that code. You can find a collectibles guide
HERE.
Code 3:03 06 09 03 06 09 03 06 09
06 03 09 06 03 09 06 03 09
The earliest this can be unlocked is after Chapter 12. This will also unlock "Hardcore Mode".