As pointed out from comments these are mostly for Samsung, I have added some for HTC below. Like I said this is just a start we can build form it. If anyone would like to create a Google Doc from this information please feel free I will add a link to this post.
SAMSUNG CODES
| Code | Description |
|---|---|
| *#*#4636#*#* | Display information about Phone, Battery and Usage statistics |
| *#*#7780#*#* | Restting your phone to factory state-Only deletes application data and applications |
| *2767*3855# | It's a complete wiping of your mobile also it reinstalls the phones firmware |
| *#*#34971539#*#* | Shows completes information about the camera |
| *#*#7594#*#* | Changing the power button behavior-Enables direct poweroff once the code enabled |
| *#*#273283*255*663282*#*#* | For a quick backup to all your media files |
| *#*#197328640#*#* | Enabling test mode for service activity |
| *#*#232339#*#* OR *#*#526#*#* | Wireless Lan Tests |
| *#*#232338#*#* | Displays Wi-Fi Mac-address |
| *#*#1472365#*#* | For a quick GPS test |
| *#*#1575#*#* | A Different type GPS test |
| *#*#0283#*#* | Packet Loopback test |
| *#*#0*#*#* | LCD display test |
| *#*#0673#*#* OR *#*#0289#*#* | Audio test |
| *#*#0842#*#* | Vibration and Backlight test |
| *#*#2663#*#* | Displays touch-screen version |
| *#*#2664#*#* | Touch-Screen test |
| *#*#0588#*#* | Proximity sensor test |
| *#*#3264#*#* | Ram version |
| *#*#232331#*#* | Bluetooth test |
| *#*#7262626#*#* | Field test |
| *#*#232337#*# | Displays bluetooth device address |
| *#*#8255#*#* | For Google Talk service monitoring |
| *#*#4986*2650468#*#* | PDA, Phone, Hardware, RF Call Date firmware info |
| *#*#1234#*#* | PDA and Phone firmware info |
| *#*#1111#*#* | FTA Software version |
| *#*#2222#*#* | FTA Hardware verion |
| *#*#44336#*#* | Displays Build time and change list number |
| *#06# | Displsys IMEI number |
| *#*#8351#*#* | Enables voice dialing logging mode |
| *#*#8350#*#* | Disables voice dialing logging mode |
| ##778 (+call) | Brings up Epst menu |
HTC CODES
| Code | Description |
|---|---|
| *#*#3424#*#* | HTC function test Program. |
| *#*#4636#*#* | HTC Info menu |
| *#*#8255#*#* | launching GTalk Service Monitor |
| ##3424# | Diagnostic mode. |
| ##3282# | for EPST. |
| ##8626337# | for VOCODER |
| ##33284# | Field trial menu. |
| ##786# | Reverse Logistics Support. |
| ##7738# | Protocol Revision. |
| ##775# | Unknown |
| ##2539# | Unknown |
One more hidden menu trick go to market download gesture (free app)
Open gesture press menu
Press settings
Enable (check) settings
Write the following in gesture: 4g
Also note writing: Sprint
And writing: settings
/u/norf9: For the s4 I found these codes:
| Code | Description |
|---|---|
| *#1234# | to check software version of phone. |
| *#12580*369# | to check software and hardware information. |
| *#0228# | Battery status (ADC, RSSI reading) |
| *#0011# | Service Menu |
| *#0283# | loopback test |
| *#06# | imei |
| *#03# | nandflashheaderread |
| *#0808# | usb service |
| *#9090# | service mode |
| *#7284# | FactoryKeystring |
| *#34971539# | camera firmware standard |
| *#1111# | servicemode |
| *#0*# | Testmodus |
if you have Verizon,
There is also an app called "Secret Codes" which will find other codes that are used by applications and not the OS itself. Some apps let you access secret settings with these codes.
These are not "Android" secret codes. These are "Samsung" secret codes. Except one of two none of them will work on any device other than a Samsung phone.
F.A.Q.
Q: So how do you enter these codes?
A: Enter using the dialer.