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Is Your SIM Card Not Working After Flashing OnePlus Custom ROM? Here’s the Proven Fix

Will Flashing ColorOS Modem Files Restore SIM Functionality on OnePlus Custom ROMs?

Many OnePlus users, especially those upgrading to custom ROMs from ColorOS, encounter SIM card detection issues—most notably on the OnePlus 13 with Nameless AOSP ROM. The root cause is typically missing or outdated modem and NV data partitions, which are essential for cellular functionality.

Why This Happens

The device’s modem and NV (non-volatile) partitions, critical for SIM and network operation, may not be compatible or up-to-date if you didn’t flash the latest ColorOS firmware before installing a custom ROM. As a result, your device fails to initialize the modem correctly, leading to no SIM detection or network access.

Step-by-Step Solution

  1. Obtain the latest official ColorOS firmware for your specific OnePlus model.
  2. Extract the firmware package to access its contents.
  3. Locate and extract oplusstanvbk.img and modem.img from the firmware files.
  4. Enable USB Debugging and OEM Unlocking in Developer Options.
  5. Back up all important data, as partition flashing carries risk.
  6. Download and extract Android SDK Platform Tools on your PC.
  7. Place both oplusstanvbk.img and modem.img in the platform-tools directory.
  8. Connect your device to the PC.
  9. Open a command prompt in the platform-tools folder.
  10. Enter:
    adb reboot fastboot

    Device will enter FastbootD mode.

  11. Flash the NV and modem images with:
    fastboot flash oplusstanvbk oplusstanvbk.img
    fastboot flash modem modem.img
  12. Complete the process with:
    fastboot reboot
  13. Your device should now recognize the SIM card and restore network functionality.

Key Points

  • Always use the latest firmware images to ensure compatibility with your custom ROM.
  • This process does not require root access, but does require an unlocked bootloader.
  • Flashing incorrect images can cause further issues—double-check device model and firmware version.