[Verizon Samsung Galaxy S 4] vacaloca:
Since VZW and Samsung Level 2 support didn't know the answer, here is how to enable the hidden menus on the dialer screen for the Verizon GS4. Previously, there was a 'master' code that enabled the hidden menus. Now it is a filesystem based check. Boo!

Due to editing /system/build.prop and /efs/carrier/HiddenMenu you MUST be rooted. Also, you must be on a stock TouchWiz-based ROM. This will not work on CM builds/etc. At a very minimum, hiddenmenu.apk must be present on your stock device for this to work, but possibly others, so beware of ROMs that remove 'bloat' APKs.

1) Add the following line* to /system/build.prop

sys.hiddenmenu.enable=1

Edit: I noticed that after I hosed build.prop, it was replaced when I loaded the default system image, so in fact, step 1 above is not necessary, at least for the Verizon variant. This means that once you do step #2 below, the changes made to /efs/carrier/HiddenMenu will persist after an Odin restore of the NoWipe Factory Image posted here. What this means is that root is only required to make the modification, and one could revert to stock afterwards with the hidden menus enabled.

2) Change the contents of /efs/carrier/HiddenMenu from OFF to ON

3) Reboot.

4) Try it out! Go to the phone dialer and enter *#06# (show MEID) as a test.

For more codes that worked on the S3 that (may) also work on the S4, see below:

http://androidforums.com/samsung-ga...unlocking-jelly-bean-service-modes-found.html

Having the hidden menus enabled is particularly useful for those who want to disable WiFi Power Saving mode -- I was having issues with an access point at work, but sadly disabling it didn't fix the problem. Otherwise, the hidden menus are useful to test your sensors/display/etc or just looking around in general. Enjoy!

For those that are NOT rooted, there is an alternative to get to SOME of these menus, but it is not a free app (currently $1.99). It's called "Sammy S Mode". Note that I am not affiliated with the developer, I just bought it to test if the menus were present before I dug deeper into finding out how to fully enable the hidden menus on my Verizon Galaxy S4. When I have time in the next day or so, I'll try to figure out how the app calls the menus, and update the post if I find a free solution for those that are not rooted.

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* Note: I added the "sys.hiddenmenu.enable=1" line right after the "persist.cne.feature=0" one, but I don't think it matters where you add it. Just be careful editing this file. I managed to get my phone boot-looping, probably because I used notepad to edit the file and it added Windows CR/LFs to it, and had to use the NoWipe Factory Image posted here to restore my phone. The second time around I used Root Explorer's built in text editor and it worked fine.

In case anyone is curious how I figured this out, click here.

Mods: Thanks for moving this to the development section since it fits better here. :)

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I wanted to compile a list of the ones that seem useful or new in general and working for me:

*#197328640# Service Mode

*#0228# BatteryStatus

*#0*# Screen/Sensor/Vibration/Touch/Speaker/LED/etc testing -- even gives out raw values for light sensor, barometer, etc in real time :)

*#2263 RF Band Selection

*#66336 MDM Randump Mode (defaults to OFF)