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If you're working with OnePlus phones for IMEI repair, QCN backup/restore, or network unlocking, enabling the DIAG port is essential. This guide explains how to enable DIAG mode on Qualcomm-based OnePlus devices using ADB commands, with and without root.

What is DIAG Mode?

DIAG (Diagnostic) mode lets tools like QFIL, QPST, UMT, Hydra, MRT, or QCN Writer communicate with your phone's Qualcomm modem.

It's used for:

• IMEI Repair / Write

• QCN File Operations

• NV Data Read / Write

• Network Unlock / Rebuild

Supported OnePlus Models (Qualcomm Only)

• OnePlus 5 / 5T

• OnePlus 6 / 6T

• OnePlus 7 / 7T / 7 Pro

• OnePlus 8 / 8T / 8 Pro

• OnePlus 9 / 9R / 9 Pro

• OnePlus Nord (Snapdragon models)

Note: OnePlus 10 and above with newer firmware may not support standard DIAG methods.

Method 1: Enable DIAG via ADB (No Root – May Vary)

1. Enable Developer Options:
   Go to Settings > About Phone > Tap "Build number" 7 times

2. Enable USB Debugging:
   Go to Settings > Developer options > Enable USB debugging

3. Connect phone to PC via USB

4. Open CMD/Terminal and run:

   Please
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   or
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   to see this code

Alternative command (for some firmware):

Please

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or

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to see this code

May not work on all OxygenOS/ColorOS versions

Method 2: Rooted Devices (More Reliable)

If your OnePlus is rooted with Magisk, use this command:

Please

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or

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to see this code

Then check Device Manager for:

Please

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or

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to see this code

How to Confirm DIAG is Enabled

1. Open Device Manager
2. Expand Ports (COM & LPT)
3. Look for: Please
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   or
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   to see this code

If not visible:

• Try a different USB cable/port

• Reboot the phone

• Reinstall Qualcomm drivers

Troubleshooting Tips

• Still no DIAG? Use root method or downgrade firmware.

• Ensure Qualcomm drivers are installed.

• On some models, you may need to enter EDL mode via test point.

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Need Help?
Reply below with your OnePlus model, Android version, and root status, and I’ll guide you step by step. Let’s make IMEI repair and QCN work easy for all!

Credits: AM19x @ GSM6