How to backup / restore Samsung Galaxy S2 EFS?

What is EFS? It is a place that stores your Android smartphone important data like Wi-Fi, Bluetooth MAC address and IMEI (nv_data.bin). Do take note if you are a frequent ROM / firmware flasher or rooted your Android phone. Installed unstable poorly cooked ROM might cause EFS partition to be corrupted or missing. Which will cause you fail to make voice call due to missing IMEI number. So better to make a backup of your EFS partition. The easiest way to backup EFS ~ just copy the whole EFS folder with Root Explorer to SD card. But some said this method is not good during EFS restore. So better use EFS backup / restore tool like kTool by Hellcat. kTool will backup the whole EFS partition (including files read / write permission) for you with 1 click. Note – root access is required.


kTool will backup EFS partition into raw .IMG dump and .tar archive at internal sdcard. And be sure to verify the EFS backup. Make sure that it is properly backup. You can also make another backup copy at your PC manually. Personally, I did not try to restore EFS function yet. Will only perform it when my phone EFS is really corrupted or missing.

Download kTool at Android Market here.

  • Ooo

    Wow,seems pretty hard to do that..

  • Nuno Ribeiro

    Hi Jayce,

    I’ve already seen it on XDA. Thanks for sharing…
    There is also another tool in XDA, the EFS Pro v1.2.6. Check this out:

    Regards from Portugal!!!

  • Dev

    i have rooted my SGSII (GT-I9100) some days back i tried flashing galnet miui ics but was stuck in bootloop so i had restored my cwm back up (back to stock rom and kernel)
    phone was working fine but today i noticed that i dont have any cellphone network for too long i tried rebooting and putting other sim card but its not detecting.

    The Baseband version, IMEI etc shows unkown. Please suggest me what to do?

    • Do you have EFS backup?

      • Dev

        nope 🙁 i dunno actually..any way to check? and any other solution other than that?

        • If no, you need to send back to Samsung for service.

  • amulya bansal

    My imei no is lost..i had backed up my efs folder via ktool and resred…bt still not able to recover imei and not able to make calls

  • amulya bansal

    i restored my imei no bt still not working…it happend before also bt that tym i didnt backed my efs files therefore i had to go to samsung service centre then they replaced my motherboard…bt if ill go again n agian to them then they will complaint and also ill feel little embaraced…plz help…i m in a lot of tension

    • Sorry, I have no idea why it is not working even after restored. Please consult kTool developer on this issue.

      • Amulya bansal

        How to consult ktool developer…..and both times my efs files got corrupted using checkrom…should i stop using checkrom from next tym

        • Email him (you can get his email at Android Market). I installed CheckROM RevoHD (several version) many times. No issue at all.

  • Rob

    Hi jayce!

    Just finished intalling the app. So both these files (.IMG dump and .tar archive) I should make a copy and put aside just in case something bad happens with the phone or which one should I keep?

    • You can keep a copy at PC. Both of them.

      • Rob

        Thanks Jayce!

  • ehknaton

    Hi Jayce,
    I used this tool to successfully backup my efs folder. Do you think this is a good way to backup /efs ?
    Because there are other tools out there like EFS Pro, or through using command line.
    This tool is just as good ? Do you use it yourself ? or you prefer other methods ?

    • Hi ehknaton, I just use this tool only. Some custom ROMs backup EFS data automatically too.

  • avinash

    hello can u help me when i rooted my micromax a52 aisha i lost imei number twice……
    please help wat can i do………….

    • Sorry avinash, I don’t have this model. No idea.