Getting to know your EFS folder on Samsung Devices

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Getting to know your EFS folder on Samsung Devices

Getting to know your EFS folder on Samsung Devices

Getting to know your EFS folder on Samsung Devices

Common Files We Back up

I am sure you have heard of critical things you need to do when you mess with an Android device right? One of the things that always come up is to back up your devices.

Backing up data usually involves making sure those contacts, calendar entries, memos, messages and special media that you may have kept within the internal memory are kept safe. The general rule when flashing and rooting is that often times, you may have to end up wiping all your internal memory data.

Some people tend to take this further and back up the internal data of apps, which is only possible if you have root access on your device. This is especially useful for those who like to play games as well as flash custom ROMs.

There are those who would also recommend that you back up the entire image of your current ROM state by making a Nandroid backup so that you can get back that exact state of your ROM if you mess up with flashing a whole new one or if you didn’t like the new ROM you tried and wanted to get back.

For Samsung devices, there is one other thing you may want to secure in a back-up chest – your device’s EFS data.

What is an “EFS”?

EFS refer to a folder location called /EFS in Samsung’s Android devices. It is a very sensitive folder hidden within the deepest core of your smartphone’s internal file system and is very essential to the functions of our smartphones.

One of the very sensitive information you can find in this folder is the information regarding your phone’s unique IMEI number.  As you may have guessed by now, it also contains other unique identifying numbers for your smartphone including the MAC address for your smartphone’s radios, as well as the MEID, ESN, as wells as the registered phone number for locked smartphones.

The Danger to EFS

Normally, the EFS folder is highly protected. Rooting and flashing ROMs normally do not touch this part of the device. Unfortunately, there is no such thing as a controlled environment where everything goes according to plan in the real world. Sometimes, a process hits the EFS folder, or ends up corrupting the data within.

The EFS is also likely to be corrupted by users who like to unlock smartphones since it usually involves editing the data within the EFS folder. Once the data is corrupted, the only way to get it back to working order is to restore the data as is.

The loss of the EFS folder may cause your phone to no longer be recognized by your carrier or some of your radios may no longer work. This breaks the device as a whole no matter how many times you reinstall a ROM.

Even if you are not planning to modify the EFS folder itself, you can still accidentally corrupt that data. That is why even if the process of rooting and flashing ROMs does not require you to do so, it would be prudent to back up the folder. This would be a classic case of being “better safe than sorry”.

Why Modify the EFS

Messing with the EFS is what you would call some “high level stuff”. People normally don’t mess with this folder due to the high risk of making the smartphone unusable. The most common use of editing the EFS folder is to unlock the smartphone so it can be used on other carriers.

Most users usually steer clear of this folder. If you really want to mess with it, look for us tomorrow as we show you how to back-up your EFS folder.

13 Comments

  1. Maxim C.says: August 9, 2013 at 9:35 am

    Hi. Just wanted to know: is not enough to install the Stock ROM via ADB once EFS was altered?

    (I read somewhere that it would be the solution)

    Since it is positioned within System partition I guess?

  2. Jonassays: July 1, 2014 at 11:28 pm

    I deleted efs folder, wiped and formatted whole tablet.
    My IMEI became 00490…..
    I bought one app from unlocksamsun……. .com, and successfully changed my IMEI to original one. I flashed ROM. WIFI works, but I can’t call. “Not registered on network”. Is it possible to repair somehow?

    • nawsà007says: July 13, 2014 at 3:18 am

      you have to install via odin MODEM file of your first original baseband version .
      for exemple ;if you had this baseband version I9500XXUEMJ8 you have to google for the file: I9500_XXUEMJ8_MODEM and put it in cp case in odin v3.09 and start

  3. Enocksays: July 15, 2014 at 9:32 pm

    I also have a problem with my Galaxy duos 7562. I deleted the efs folder and now have got this yellow text on a transparent window with information such as PDA,SCS, ….. How do I revert back to normal. I dont have the efs folder backup

  4. Ashadsays: September 15, 2014 at 1:42 pm

    I have a backup of my EFS but due to tampering with that folder, my phone wont start anymore
    So is there anyway that i could fix this Issue?

  5. Andrew Maslinsays: April 6, 2015 at 11:36 am

    I have a Samsung Galaxy S2 my phone has been messed around with over time (ie somebody in China managed to make my phone sim free, i dont know how?) but now I’m back in UK and have been trying desperately to get my phone sim free, myself.. It seems to me that the phone requires it to be rooted, I am a beginner newbie to how to do this, and have tried hard to finding info how to do this (make sim free).. My phone was originally with 3 network in UK My phone is now rooted (Cynamod), i have tried various apps online which claim to unlock phones but with no luck. the phone does not ask for any codes when i start the phone, only that when i try to make a call the phone says i’m not registered to the network, I have tried to placed the sim card in another phone, and the sim card worked fine? When i have read about various codes online to input numbers into the phone keypad for information about the phone e.g NOT REAL CODE(*#54646#) My phone does nothing!!!( although i can recall the IMEA number!!!!! But this number does not match the IMEA number which is behind the battery in the phone!!!! When rooting my phone i think i saw a folder called “efs backup” is this the problem or answer to my problem??? I dont know what this does? But I’m guessing it may have something to do with solving my problem……Please Please if someone could help me with this, it would be a life saver i cannot affor to buy another phone at this point, and just want my GS2 to work correctly, thank you so much for any help and advise you can give!!

    • Andrew Maslinsays: April 6, 2015 at 11:54 am

      I have just checked my efs back up file and i also had a folder called clockworkmod looks like they were all wiped out when trying to call all i get is “Mobile network not available” what can i do? Please give detailed answer if you can i am a newbie thank you..

  6. Stefansays: April 11, 2015 at 7:34 pm

    I installed some custom roms on my phone (I9505 S4). Someday when it was turning on some kind of “Factory Mode” error appared on the screen the after some seconds it just vanished. Every time it boots I must manually turn on the WIFI. In root explorer I can’t see any EFS folder but wifi, bluetooth and IMEI are just fine (the IMEI is the same as it is on the phone).
    What can I do to stop this annoying error?

  7. Arnold Sujan Katrusays: July 17, 2015 at 6:38 pm

    hie guys
    Please Help Me I am using Samsung Star Pro S7262. and roited it but i tried to install Beast Kernel v.3.1+Moule to my rom it has done well. but my bad is i forgot to backup my efs .but i still have some wifi mac address showing on and imei nubers are all 0(zeros) so help if i can create new efs file to create a new backup.and i know the real imei no. as it is with my oacking box. Please sir Help me with this ASAP.

  8. Arnold Sujan Katrusays: July 17, 2015 at 6:38 pm

    hie guys
    Please Help Me I am using Samsung Star Pro S7262. and roited it but i tried to install Beast Kernel v.3.1+Moule to my rom it has done well. but my bad is i forgot to backup my efs .but i still have some wifi mac address showing on and imei nubers are all 0(zeros) so help if i can create new efs file to create a new backup.and i know the real imei no. as it is with my Packing box. Please sir Help me with this ASAP.

  9. Arnold Sujan Katrusays: July 17, 2015 at 7:06 pm

    SIR i have a samsung star pro s7262 i rooted it and flashed a custom rom from xda everything gone fine but i tried to install custom Beast Kernel v2.1+module it was all installed fine but when i see an weird message on screen was with a yellow out line .And there know that i forgot to Backup my Efs it all gone shit .i have 00000000000 in my imei number and i still able to see wifi mac address and bluetooth address were there. Please help me how to recovery the Efs or How to Create New Efs folder i stil have the lost imei numbers. So
    Please Help Me AsAp.
    Thanks A Lot In Advance.

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