Sony Xperia SP: How to Relock Bootloader

Sony Xperia SP is now getting its availability wider in more countries. More important is to get the attention from 3rd party developers for this device as you can have wider choice of custom rom, tweak and mode for Sony Xperia SP. We already getting our hand on how to root Xperia SP and installing ClockWorkMod on Xperia SP in our previous posts to prepare for the flashing of custom rom once it is available.

Nevertheless, you might also want to receive official update from Sony after a long time of getting your Xperia SP with variety of customized rom. In such a case, a relock bootloader process is necessary to be implemented. Your device is only receiving an official update via PC Companion or Sony Update Service under the condition of relock bootloader. In this tutorial, we will show you how to relock bootloader of Sony Xperia SP using Flashtool.

Relock bootloader will not terminate the root access on your device but some apps will work improperly i.e RootExplorer v3.0 will reboot when trying to mount/system as rw. You have been reminded of the possibility of getting your 3rd party application malfunction after relock bootloader.

In order to proceed to the next section, please ensure your device is with stock kernel. In case you have flashed a custom kernel, you might need to flash back to stock kernel before relock bootloader using our tutorial below.

How To Relock Bootloader on Sony Xperia SP

Disclaimer: It’s always a risk to modify your device. We, Android Teen are not responsible for any damage or bricks on your device. Your device warranty may void with any mod. Check your devices warranty’s term & conditions before start.(HTC,Samsung,LG, Sony, Motorola). Use this guide on your own risk, contact us for help if you face problem.

Pre-requisites & Requirements

  1. Sony Xperia SP – with stock kernel (Ensure correct device model and firmware; Check device model – Go to Settings -> About Device -> Model Number)
  2. Windows-based computer or laptop
  3. Download Sony Xperia SP USB driver for Windows and install in your computer.
  4. Connect device to computer with USB cable to complete installation.
  5. Skip this step if you have installed the USB driver.
  6. Enable USB Debugging on your device. How to Enable USB Debugging Mode on Android Devices.
  7. Make sure your phone is charged to 60% 80% to avoid battery blackout and interruption during this tutorial.
  8. We recommend you make a backup on your data and media files before the tutorial. You may restore the data and files if necessary.

Reminder: Ensure you make a backup before proceed. Besides that, ensure you meet the requirements before proceed. Contact us if you face problem.


  1. Sony Flashtool (flashtool- | 112.77MB)
  2. Relock Bootloader (Xperia_SP_Relock_Bootloader.ftf | 62.44KB)


  1. Download Sony flashtool into your computer. Double click on the flashtool.exe file to install. You should see a flashtool folder in C Drive.
  2. Double click on flashtool icon in the folder mentioned in Step 1 to launch flashtool.
  3. Enter to Fastboot Mode on your device by press and hold Volume Up button while connect your device with USB cable to computer. You should see blue led light.
  4. Download Xperia_SP_Relock_Bootloader.ftf and copy to flashtool/firmwares folder in computer.
  5. On the flashtool, click on the lightning icon and click fastboot mode, then “ok”.
  6. Click “Select kernel to Flash” on right side in flashtool.
  7. Browse and choose “Xperia_SP_Relock_Bootloader.ftf ” in the flashtool/firmwares. Xperia_SP_Relock_Bootloader.ftf  will be flashed to your device.
  8. Your device should be reboot automatically after flashing tft file.
  9. To check the bootloader status, open dial pad on your device. Key in *#*#7378423#*#*, go to Service Info –> Configuration. You shall see the bootloader status.

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A 17 years old young tech enthusiast who loves Android and smartphone. He love to learn and share Android latest technologies to public users. He likes to play around with custom ROM flashing, customize theme, system tweaking and discussion with other developers on Android development. Now, he owns Galaxy S3, LG Optimus L5, Sony Xperia Z and pre-owned Sony Xperia P, HTC One X, LG Optimus G.