How To Install Android 4.0.4 ICS Sony Xperia U ST25i CyanogenMod 9.1

Android 4.0.4 ICS CyanogenMod 9.1 for Sony Xperia U ST25i? Yes, now there’s a CM ROM for this device. If you need vanilla, and hate the Sony’s stuff, this is a good custom ROM. CM has the exact same user interface on the Nexus series devices. Because all of them are uses the AOSP, which mean Android Open Source Project.

This after market firmware doesn’t have the popular Google’s applications. For an instance Play Store, sync. Because they are not in the AOSP. Although you can install them using this tutorial contain Gapps zip file. It’s not an a illegal method. Moreover it doesn’t have Sony stock apps. As I mentioned above sentence if this is built from AOSP firmware, all the CM ROM has extra useful customization options. Unlike the Stok ROM, this Sony Xperia U ST25i and ST25a ROM optimized better performance with good battery life.

Like other Cyanogen ROM’s this one also has its own kernel. We call it CM kernel. You can find it inside the ROM file (boot.img). Therefore you have to unlock bootloader. I already published step by step unlock Xperia U bootloader tutorial. You can reference it for more information. Without unlocking, you can’t follow this installation.

If your Xperia U doesn’t root and there is no custom recovery, you can flash this CM9.1 ROM. Because of CM9.1 kernel has CWM-based recovery moreover that kernel support root access. If this is uses the CM name, it’s not an official version from that team. This ROM developed by the XDA forum “FXP” member.


  • Installing custom firmware voids Xperia U warranty.
  • This is not a risky installation, but if you make any mistake, it can be a serious issue.
  • Applying my tutorial at your own risk. I can’t take any responsibility.





  • Free Xperia Project [ FXP ] CM9.1 in here. [ The Xperia U code name “kumquat” search that name contains a zip file in the download page ]. If you face any issue while download files, use jDownload manager ].
  • Google apps zip file in here.
  • Fastboot files in here.



How to install Xperia U ST25 Android 4.0.4 ICS CyanogenMod 9.1 ROM.


This installation has two steps. Install kernel and install CM9.1 ROM zip file. If your phone already installed any custom recovery, you can start it from after boot into the recovery. Because your device can install the kernel via custom recovery. No need to use fastboot.

  • Before starting the Cyanogen installation unzip fastboot zip file to the desktop.
  • Get the CM9.1 kernel file. It’s packed in the ROM zip file. You can do it extracting zip file contain “boot.img” file.
  • Save the ST25 CM kernel with fastboot.exe file.
  • Copy Cyaongen ROM and ICS Gapps zip file into the Xperia U SD card [ Internal memory ].
  • Disconnect phone from the PC and then power off..
  • Connect the Xperia U to the PC over USB while you are pressing the Volume Up button.
    • LED turn to “Blue” .
    • Open the fastboot exe files folder.
    • Press and hold the “Shift” key and right click inside that folder.
    • When you see the Windows context menu. Click its “Open command window here” option.
    • Then Windows Command Prompt” [ CMD ] window will open.
    • Use following command line to install the kernel.
fastboot flash boot boot.img
  • Then apply following command to reboot it.
fastboot reboot
  • IF you already uses CWM or TWRP, you can start the installation from here.
  • Next we should boot into the recovery. When the Xperia U booting, rapidly press and release the “Volume Up“.
  • After you enter into the CWM based recovery,
    • Go to “backup and restore>Backup”. It will take a few minutes.
    • Navigate to “Wipe data/factory reset>Yes – Wipe user data”.
    • Go to “Wipe cache partition>Yes – Wipe cache”.
    • Navigate to “Advanced>Wipe dalvik-cache>Yes Wipe”.
    • Go to “Install zip from the sd card>Choose zip from sd card”. Browse the ROM zip file and select “Yes – Install.
    • Again select “Choose zip from sd card” install the previously copied Android 4.0.4 ICS “” file.
    • Select “reboot system now” option.
  • Congratulation, you just installed CyanogenMod 9.1 on your Sony Xperia U ST25i.


While you are updating your phone, you don’t need to follow wipe data/factory reset. However Google apps installation is a must.

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