If you are fond of custom Android modifications such as custom ROMs or custom scripts and install them on your Android mobile for additional features or increased performance, then it would be a nice and wise decision to backup EFS (IMEI) and Modem partitions of your Android mobile before flashing any custom modification on it. This backup can be used to restore EFS and Modem partitions in the future.
Note: This tutorial is not intended for those who have already lost their EFS (IMEI) partitions. We will be publishing a separate post for them very soon. If you are one of them, comment below or subscribe to our newsletter to get updates on the same.
Update: For some reason, ES File Explorer has been removed from Play Store. We replaced it with File Explorer Root Browser by JRummy.
Table of Contents
While installing custom ROMs and custom modifications is fun, it can create serious problems in certain situations. Situations like using unstable/buggy recovery or installing alpha/beta versions of modifications on your Android mobile.
Following are the serious problems that may arise in above stated situations.
- No signals
- No SIM detected
- No IMEI number
- Corrupted EFS/IMEI data
- Unknown Baseband
- Yellow screen
- Wi-Fi and Bluetooth issues
Before getting into the detailed procedure, lets learn few things about the EFS and Modem partitions and the problems that could arise when someone messes up those partitions in an Android device.
EFS stands for Encrypting File System. It is an important part of Networking and Communication in an Android mobile. It also contains device IMEI (International Mobile Equipment Identity) data, which is necessary for network communications.
For detailed information on EFS, read Encrypting File System – Wikipedia.org article.
What happens when you corrupt EFS/IMEI data
It is always recommended to backup EFS (IMEI) data to a safe place before installing custom ROMs and/or modifications on your Android mobile. Because these are the places where you might loose or even corrupt the data.
When you corrupt or lose the data present in these places, you may no longer be able to use your smartmobile for communication i.e, you won’t be able to make a call and utilize Internet services, reducing the device to just a multimedia toy.
A Modem is also referred to as a radio or a baseband. It is a driver that modulates and demodulates the carrier network signals. It is used to control network signals and to switch between GPRS, 3G and HSDPA in a mobile device. It does not control Wi-Fi or the switchover between mobile signals and Wi-Fi.
For detailed information on Modem, read Modem – Wikipedia.org article.
What happens when you corrupt Modem partitions
Along with EFS partition, we recommend you to have a backup of Modem partitions because these partitions also contains radio related data and you might corrupt these partitions in the process.
When you corrupt Modem partitions, network problems arise. Network problems like loosing network signals, SIM card detection issues, unknown baseband, Wi-Fi/bluetooth connection issues etc.
Want to know your Modem details? Switch on your Android mobile and go to Settings > About phone > Baseband version.
Now, as you know the importance of your mobile EFS (IMEI) and Modem partitions, you should and must backup EFS and Modem partitions of your Android mobile to a safe place before installing any custom modification.
Your mobile should meet the following requirements in order to backup and restore EFS and Modem partitions.
- Android mobile with root access.
- File explorer with root access, preferably ‘File Explorer Root Browser’.
- External or internal memory card.
Backup EFS (IMEI) and Modem Partitions of Android Mobile Devices
Note for GT-S7262 users: EFS, Modem and Modem-2 partitions of Samsung Galaxy Star Pro/Plus GT-S7262 mobile are interlinked for unknown reasons while using Stock ROMs. Hence, you should backup all the 3 partitions to restore them whenever you encounter network related problems like IMEI lost, yellow screen etc.
Follow the below procedure to backup EFS (IMEI) and Modem partitions.
- Install Partitions Backup & Restore, and File Explorer Root Browser apps from Google Play Store on your Android mobile.
- When asked for, grant root access to both the apps.
- Launch Partitions Backup app and then click on the Settings icon present on the top right corner of the app.
- Select External SdCard as backup path (if SdCard available) else select Internal SdCard.
- Then select Highlight all related IMEI/EFS partitions.
- Now select Raw partition image (img) as backup format.
- Click on the back button.
- For GT-S7262 users: Select EFS, MODEM, MODEM2 partitions (yellow colored).
For others: Select EFS and other appropriate partitions (yellow colored).
- Then click on the Download button present on the bottom right corner of the app. The app will now backup EFS and related partitions to the selected memory card.
That’s it. You should now have a copy of your backed up partitions in the selected format in the selected memory. You should now copy these backed up partitions to a safe place like a computer or a laptop for future use.
Restore EFS (IMEI) and Modem Partitions of Android Mobile Devices
To restore EFS (IMEI) or Modem partitions of your Android mobile, you should already have backups of EFS (IMEI) or Modem partitions either in image (img) or raw format.
Follow the below procedure to restore EFS (IMEI) or Modem partitions of your Android mobile.
- If not already present, copy the backed up partitions stored on a safe place like a computer or a laptop to the ‘Partitions Backup’ folder present on the mobile memory.
- Launch the Partitions Backup app and click on the 3-dot button present besides the settings icon.
- Select Restore a Partition option and then OK option.
- Now select File Explorer Root Browser option and then select Just Once option.
- Choose the memory where the backup is present i.e, internal memory or external memory, and then select Partitions Backup folder. This is the default location where the mentioned app saves the backed up partitions in selected format.
- For GT-S7262 users:
- EFS: To restore EFS partition, select the EFS backup file from the folder and then select efs (mmcblk0p3) partition. Finally click on Restore option.
- MODEM: To restore Modem partition, repeat the steps 2,3,4,5 and then select the Modem backup file from the folder. Now select modem (mmcblk0p7) partition and then finally click on Restore option.
- MODEM2: To restore Modem-2 partition, repeat the steps 2,3,4,5 and then select the Modem-2 backup file from the folder. Now select modem2 (mmcblk0p11) partition and then finally click on Restore option.
- For others:
- EFS: To restore EFS partition, select the EFS backup file from the folder and then select efs (xxxxxxxx) partition, where xxxxxxxx is the partition name of your Android mobile. Remember to select the exact target partition as the input backup file. If everything is in correct place, click on Restore option.
- Repeat the similar steps for other partitions (if any).
- Reboot your mobile.
That’s it. You should now have a working mobile. Restoring a partition (in its corrupt state) using its previous backup should fix network related issues. If you still face any problems, repeat the above process and then clear your mobile cache and dalvik-cache and then reboot your Android mobile.
Note: If you think that you have made a mistake while restoring partitions and your mobile is now stuck at bootlogo, then reboot your mobile in recovery mode and restore your partitions from CWM recovery or TWRP using the backup files present on the mobile memory.
That’s it for today. Hope you will find this small but useful guide useful. Share it with your family and friends.
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