MMI or Man Machine Interface codes are useful when you want to access information about your Android phone or enable or disable certain features. But why is your phone showing the "Connection Problem or Invalid MMI Code" error?
This could happen due to a network glitch, SIM card malfunction, or a misbehaving app, among other reasons. No matter the cause, the solutions below will help you fix the issue.
1. Edit the Code
MMI codes aren't easy to remember, so there's a chance you typed in the wrong code. Take a second and check if you've entered the right MMI code.
Alternatively, you can add a comma after the code and see if it works. For example, if you want to try *#*#4636#*#* to check information about your phone's data usage, type in *#*#4636#*#*, before dialing.
2. Enable and Disable Airplane Mode
There's a chance your Android device has run into the "Connection Problem or Invalid MMI Code" error due to a temporary network mishap. Most of the time, refreshing the network connections by enabling and disabling Airplane mode should fix the issue.
Access your phone's Quick Settings menu and tap on Airplane mode. Wait for a couple of minutes and disable it. Additionally, you can access Airplane mode by heading to Settings > Connections on your Android device.
3. Toggle Your SIM Off and On
When encountering network issues on your phone, you can try turning off and on your SIM card. Open your phone's Settings app and go to Connections > SIM manager. Here, turn off the toggle next to your SIM, wait a couple of minutes, and turn it back on.
4. Enter the Code in Safe Mode
A malfunctioning third-party app might be the reason why you encounter the "Connection Problem or Invalid MMI Code" error. To test it, try entering the code in safe mode.
Open the Quick Settings menu and tap on the Power icon. Then, tap and hold Power off until you see the Safe mode icon. Tap it to restart your phone in safe mode.
Once your phone restarts, try dialing any MMI code. If it works now, you have to uninstall the problematic app. While you're at this, it's worth finding and uninstalling apps you never use.
5. Reset Network Settings
If you still can't get MMI codes to work, consider resetting your Android phone's network settings. However, you should know that resetting your network settings will remove paired devices, data limits, and Wi-Fi passwords, among other network values.
Fix Invalid MMI Codes on Your Device
MMI codes can be very useful, especially if you have to service your phone and need software and hardware information. Now, if you still can't get MMI codes to work, you'll need to contact your network provider for carrier-specific instructions. There's a good chance your carrier will offer you a new SIM card.