Secret codes are hidden codes on your Galaxy S4 which will help you to configure, to get information or to test an inbuilt hardware functionality which is not possible normally. It’s always risky to play with secret codes without knowing what it will do to your phone, so be cautious.
How to enter secret codes?
Before proceeding, please see the below screenshot to get an idea how you can enter the codes.
So just type the code to your normal dialing keypad, that’s it the code will just execute.
If any of the codes are not working or you have any other useful codes with you which are not published here, please feel free to post it in the comment section below so that everybody will benefit from it.