If you’ve grabbed the opportunity to upgrade your Samsung Galaxy S2 to Android 4.0.3 Ice Cream Sandwich build XXLPB, you’ll be happy to know that it’s also easy to root.

Android 4.0.3 XXLPB firmware is a recent unofficial update for the Samsung Galaxy S2, offering a more improved firmware compared to earlier updates. If you applied the update to your phone, you would have lost your root access, but read on to know how to regain root on your Galaxy S2.

Before you root your device, make sure to backup of all your phone data and files.

System tools such as Samsung KIES, firewall programs, and antivirus software may block your computer from communicating properly with your device. Disable such software for the meantime to ensure a successful root.

Lastly, pump-up your battery to at least 60% to keep your device running throughout the entire rooting process.

The instructions in this guide are for the Samsung Galaxy S2 GT-I9100.  These may or may not work with variants.  Also, the method here applies only to the Galaxy S2 running the XXLPB firmware.

If you’re ready, you may now proceed to rooting your Samsung Galaxy S2 running Android 4.0.3 build XXLPB.

Instructions

After following these instructions, your Galaxy S2 will be rooted, the Superuser app will be installed, and ClockworkMod Recovery will also be flashed on your phone.

1. Download the CF-Root kernel here and save it to your computer (CF-Root-SGS2_XX_OXX_LPB-v5.2-CWM5.zip, 6.23 MB)
2. Unzip the downloaded file and you will get CF-Root-SGS2_XX_OXX_LPB-v5.2-CWM5.tar. Take note that you will only need to unzip the file once. The .tar file will be needed to root your device. If you extracted a zImage file, it means you have also unzipped the .tar file.
3. Download Odin3 v1.83 here and save it to your computer (Odin3-v1.83.exe, 416 KB).
4. Turn off your phone. Wait until it vibrates to confirm that it is completely turned off.
5. Boot your device into Download mode by holding the Volume Down key, Home key, and Power button simultaneously until a “Warning!” sign appears.
6. Press the Volume Up key to continue.
7. Open Odin3 by double-clicking “Odin3 v1.83.exe” on your computer.
8. Hook your phone to the PC via USB cable. The word “Added!” will appear in Odin’s message box. If no such message is shown, make sure the appropriate drivers for your phone are installed on your computer.
9. Click the PDA tab in Odin and select the .tar files you extracted earlier.
10. Under “Option”, check the Auto Reboot and F. Reset Time checkboxes.
11. Click the Start button in Odin3 to install the CF-Root kernel. A “PASS” message will appear when the kernel is successfully installed.
12. Your phone will automatically reboot once the kernel is installed.
13. Unplug your phone from the computer once the Samsung Galaxy S2 logo appears.

Congratulations! You have successfully rooted your Samsung Galaxy S2 with Android 4.0.3 XXLPB firmware. Superuser and ClockworkMod Recovery have also been installed in your device. You can now fully enjoy root privileges on your Galaxy S2 running Android 4.0.3 Ice Cream Sandwich XXLPB firmware.