Fingerprint on Xiaomi Mi 9T: full setup and problem solving

The Xiaomi Mi 9T fingerprint scanner is one of the key security features that allows you to unlock the device in a split second. However, not everyone knows how to properly configure this sensor to work smoothly. Unlike traditional button scanners, the Mi 9T has an integrated optical sensor under the screen, which requires a special approach to fingerprint recording.

Many people face problems: the sensor does not recognize the finger the first time, there are errors when adding a new fingerprint or the scanner completely stops responding, most often due to improper recording techniques, screen contamination or software failures. In this article, we will discuss not only the basic setting, but also the hidden functions of the scanner, as well as ways to fix typical problems.

Preparing the smartphone before setting up the fingerprint

Before you start adding a fingerprint, make sure your Xiaomi Mi 9T is ready for the procedure. Failure to follow simple rules can cause the scanner to malfunction or not recognize the finger at all.

First, check the screen clean in the sensor area (usually the lower center of the display). Fat spots, dust or protective film can block the infrared radiation of the sensor. Use a lilaless wipe and alcohol solution (at least 70%) for cleaning. Avoid aggressive detergents - they will damage the oleophobic coating.

Second, update your firmware to the latest version. There were bugs in older versions of MIUI that caused the fingerprint scanner to randomly shut down. To check for updates, go to Settings → About Phone → System Update.

• 🧴 Clean the screen – remove greasy traces and dust from the scanner area.
• 🔋 Charge the battery – at a charge level below 20%, the system can restrict background processes, including biometric authentication.
• 📱 Remove the case - some cases with metal inserts interfere with the sensor.
• 🔒 Set a pattern lock or PIN — Without it, it is impossible to add a print.

⚠️ Note: If you recently dropped your phone or noticed cracks in the scanner area, the fingerprint may not be added. Optical sensors are sensitive to physical damage - in which case you will need to replace the display.

Step-by-step: how to add a fingerprint

The process of registering a fingerprint on the Mi 9T is intuitive, but there are nuances that affect the quality of recognition.

1. Open Settings → Passwords and Security → Fingerprint.
2. Enter the current one. PIN-code or pattern lock for confirmation.
3. Click Add Fingerprint and select a finger (e.g., right index hand).
4. Place your finger on the scanner area (it will be illuminated in green) and hold it still until you feel the vibration.
5. Raise your finger and repeat the action by slightly changing the angle of the application, and the system will request at least 30% of the surface of the finger.
6. After successful recording, click Ready.

Important: Don't press too hard, because Xiaomi's optical scanners fire a light touch. If the sensor doesn't respond, try to brighten the screen (in dark conditions, the scanner works worse).

Is the phone case taken off?

Is the battery level sufficient?

Is the scanner area on the screen clean?

Is it properly administered? PIN-code

Is the firmware updated to the latest version?-->

If the system gives an error "Can't add a fingerprint", try:

• 🔄 Restart the phone and repeat the procedure.
• 👆 Register another finger (for example, a thumb instead of an index finger).
• 📵 Temporarily disable the power saving mode in Settings → Battery.

Optimization of the scanner: secret settings

Few people know, but MIUI has hidden parameters that allow you to improve fingerprint recognition, for example, you can increase the speed of the sensor response or disable the unlock animation.

For this:

1. Activate Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times.
2. Back to Settings → Additionally. → For developers.
3. Find the item Animation unlock fingerprint and disable it – this will speed up the system response.
4. In the same menu, enable Improved fingerprint recognition (if available).

On the Xiaomi Mi 9T with MIUI 12.5+ firmware, there is an undocumented “Adaptive Scanner” feature – it automatically adjusts the sensor sensitivity to the humidity of the finger or the brightness of the lighting. To activate it, after adding a fingerprint, restart the phone and wait for the system optimization (it takes ~ 5 minutes).

⚠️ Attention: If you use dark wallpapers with a predominantly black color, the scanner may be slower. AMOLED-It's a screen that turns off the pixels when you display black. Try changing the wallpaper to lighter ones.

How to remove or change saved prints

If you need to remove an old print (for example, when changing your phone user) or overwrite it, do the following:

1. Go to Settings → Passwords and Security → Fingerprint.
2. Enter. PIN-proof-code.
3. Click on the print you want to remove and select Remove.
4. To change, simply add a new fingerprint of the same finger – the system will automatically overwrite the old data.

Note that if you delete all the prints, biometric unlocking will be impossible until you add a new one, and remember that once you reset your phone to the factory settings, all the prints will be erased.

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If the scanner stopped recognizing the finger after the MIUI update, try removing and re-addling the fingerprint, often solving the problem without resetting the settings.

Problem Solving: Scanner Fails to Work or Recognition Errors

Even after setting up correctly, the fingerprint sensor on the Mi 9T can fail.

Problem 1: The scanner does not respond to the touch

• 🔌 Check the connection of the plume - if the phone fell, the sensor plume could move away (disassembly is required).
• 📱 Reset your biometrics settings: Settings → Passwords and security → Resetting the fingerprint settings.
• 🔄 Reverse to the old firmware if the problem appears after the update.

Problem 2: The fingerprint is only recognized after 5-10 attempts

• 🧼 Re-write the print, washing and drying your hands.
• 🌡️ Check the temperature of the phone – when overheating, the scanner turns off.
• 🔦 Increase the screen brightness to maximum during setup.

Problem 3: After the screen is replaced, the scanner does not work

This is a common situation, because the original screens for the Mi 9T come with a pre-paired scanner, and if the wizard has installed a non-original display or has not connected the sensor through service software, the scanner will not work.

• 🛠️ Contact Xiaomi Service Center to Reactivate Sensor.
• 📲 Install custom firmware with support for non-original scanners (for example, Pixel Experience).

Security: How to protect data when using a fingerprint

Biometric authentication is convenient, but it's not always secure. PIN-If you're not using the code, you can't change your fingerprint if it's compromised:

• 🔐 Use the complex PIN (at least 6 digits) as a backup method of unlocking.
• 🚫 Do not register the fingerprints of strangers, even temporarily.
• 🔄 Renew the prints periodically (once in a week) 3-6 months), as the shape of the finger may change.
• 📱 Disable fingerprint unlock for applications with sensitive data (banks, instant messengers).

MIUI has a Safe Zone feature (some regions call it Private Mode) that allows you to hide selected applications with additional biometric verification to activate it:

1. Go to Settings → Privacy → Private mode.
2. Turn on the feature and add the apps you want to hide.
3. Set up unlocking via print or PIN.

⚠️ Attention: If your Mi is yours 9T stolen, an attacker can unlock it with your fingerprint (e.g. while you sleep).To avoid this, set up automatic deletion of all biometric data after 5 failed input attempts PIN-code.

Alternative Unlocking Methods for Mi 9T

If the fingerprint scanner is out of order or you prefer other authentication methods, the Xiaomi Mi 9T supports several alternatives:

• 🔑 pattern lock – convenient, but less secure than PIN.
• 🔢 Digital. PIN-code – minimum length of 4 characters, recommended 6+.
• 👤 Facial recognition – works through a front camera (less reliable than a print).
• 📍 Smart Lock – Automatic unlocking in trusted locations (e.g. at home).

To adjust facial recognition:

1. Go to Settings → Passwords and Security → Face Recognition.
2. Follow the instructions on the screen while holding your phone at eye level.
3. Record your face under different lighting conditions (this will improve recognition).

Note: facial recognition on the Mi 9T only works in good lighting and does not support infrared lighting (unlike Xiaomi’s flagship models).

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Fingerprint is the most reliable method of biometric authentication on the Mi 9T, but its effectiveness depends on the correct setting and care of the sensor.

FAQ: Frequent questions about the Mi fingerprint scanner 9T