Fingerprint scanner on Xiaomi Redmi 9T: full setup and troubleshooting

The Xiaomi Redmi 9T fingerprint scanner is not just a convenient way to unlock, but also an additional layer of personal data protection. However, many users face problems: the device does not recognize the fingerprint, the sensor does not work with delays or does not respond to touch at all, most often due to improper settings, sensor contamination or software failures.

In this article, we will look at all the steps of scanner configuration, from basic fingerprint registration to solving common errors, how to add multiple fingerprints, why the sensor may not work after an update. MIUI, What to do if the system requires you to enter PIN-We're going to focus on the hidden functions instead of the scanning. MIUI 12/13/14, which allow faster recognition and improved sensor accuracy.

If your Redmi 9T ignores fingerprints or gives you a "failed to add a fingerprint" error, don't rush to bring your phone to the service. 90% of the time, you can solve the problem yourself in 5-10 minutes. Let's start with the basics.

Preparing the smartphone before setting up the scanner

Before registering fingerprints, make sure your Xiaomi Redmi 9T is ready for the procedure.Missing these steps often leads to sensor malfunctions or the inability to add a fingerprint.

Basic requirements:

• 🔋 Battery charge at least 20%. At low charge, the system can interrupt the registration process.
• 🔒 The phone should be installed. PIN-A code, a pattern lock or a password, without which the fingerprint scanner will not activate.
• 🧼 Sensor and finger cleanliness: Fat marks, moisture or dirt interfere with proper scanning.
• 📱 Updated version MIUI. Old firmware may lack critical fixes for sensor.

Pay special attention PIN-If you forget it, first reset through Mi Account (associated Xiaomi account). Without a valid unlock code, you can't set up the scanner.

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If the fingerprint sensor doesn’t respond to touch, try restarting your phone in Safe Mode (hold the power button → “Reboot Safe Mode”). This will help eliminate the impact of third-party apps.

Also check if the Power Saving mode is activated in the battery settings, which in some versions of MIUI restricts the operation of biometric sensors.

Step-by-step: how to add a fingerprint

The process of registering a fingerprint on the Redmi 9T takes no more than 2-3 minutes, but requires accuracy.

1. Open Settings → Passwords and Security → Fingerprints.
2. Enter the current one. PIN-proof-code.
3. Click Add a fingerprint and select a finger (e.g., Big Right Hand).
4. Hold your finger tightly to the sensor (located on the back of the camera). Hold it until it vibrates.
5. Raise your finger and repeat the action by changing the angle of touch (finger edge, center).
6. Wait for the message Fingerprints added (usually 8-12 touches are required).

Important nuances:

• 👆 Don’t push the sensor too hard – it distorts the scan.
• 🔄 If your finger is wet or dirty, wipe it and the sensor with a dry wipe.
• ⚡ When registering, use the same angle at which you will unlock your phone.

After successful registration, check the scanner: lock the screen and try to unlock it with a fingerprint. PIN-Reboot it, it’s a temporary bug. MIUI.

Configure additional parameters of the scanner

By default, the fingerprint scanner on the Redmi 9T only works to unlock the screen. However, MIUI has hidden features that extend the sensor's capabilities:

To activate the unlocking of applications:

1. Go to Settings → Applications → Blocking applications.
2. Set the switch to the On position.
3. Select applications from the list (e.g. Gallery, Messages).
4. The next time the application is opened, the system will request a fingerprint.

If any features are missing, upgrade MIUI to the latest version or check the firmware region (Chinese versions may have restrictions).

Removal and re-registration of fingerprints

Sometimes the scanner will start to fail to recognize the fingerprint due to data damage or a change in the topography of the finger (for example, after a cut), in such cases, a complete re-registration will help:

1. Open Settings → Passwords and Security → Fingerprints.
2. Enter. PIN-code.
3. Click on the saved print and select Remove.
4. Add the print again, following the instructions in the section above.

When you need to remove the fingerprint:

• 🩹 Finger damaged (cut, burn, callus).
• 🔄 The scanner stopped recognizing the fingerprint after the update MIUI.
• 👥 The phone is used by another person (for example, selling the device).
• 🛠️ After repairing the back panel (the sensor calibration could have been lost).

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Deleting all fingerprints resets the biometrics settings for applications and payments, and once re-registered, they will have to be reconfigured.

If after removing the fingerprint, the scanner stopped working at all, reset the security settings:

1. Go to Settings → Passwords and Security → More.
2. Select Reset Security Settings.
3. Confirm the action. PIN-code.

Solving problems with the fingerprint scanner

Even when set up correctly, the sensor may not work properly, and let's look at some of the most common errors and how to fix them:

Diagnostic algorithm:

1. Check the cleanness of the sensor and finger.
2. Make sure there is no case on the phone that covers the sensor.
3. Restart the device in Safe Mode (if the problem has disappeared, it is the fault of third-party software).
4. Update MIUI to the latest version.
5. Reset your security settings (see the previous section).

If neither method works, the sensor plume or the sensor itself may have failed, and this requires a diagnosis at a service center. 9T — 1 500–2 500 ₽ (depending on the region).

Calibration of the fingerprint sensor (hidden function)

MIUI has an undocumented ability to calibrate the scanner, which improves recognition accuracy, which helps if the sensor becomes less responsive after updating or mechanically impacting.

Calibration instructions:

1. Open the phone keyboard and enter the code ##6484##.
2. In the menu that appears, select Fingerprint Test.
3. Follow the instructions on the screen: Put your finger on the sensor from different angles.
4. After the test is completed, restart the phone.

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Warning: Do not use this code on the Chinese versions of Redmi 9T (model M2010J19SG). It may cause a firmware malfunction. Before entering, check the region of your device in Settings → About Phone → MIUI version.

Calibration resets the sensor's internal settings, so after the procedure, you have to re-register all the fingerprints, but in most cases, this solves the recognition problems.

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If the code ##6484## doesn't work, try an alternative method: in Settings → About your phone, tap the kernel version 5 times. This will open a hidden test menu.

Alternative ways to unlock if the scanner is not working

If the fingerprint sensor is out of order or temporarily unavailable, set up backup unlock methods:

• 🔢 PIN-code: the most reliable option. Set the code of 6+ numerals in Settings → Passwords and security → Screen locking.
• 🖼️ pattern lock: convenient, but less secure. Do not use simple patterns (e.g., the letter "Z").
• 👤 Trusted Face (Face Recognition): Works in Settings → Passwords and security → Facial recognition. Minus doesn't work in the dark.
• 📍 Smart Lock: Automatically unlock in trusted locations (home, work). → Passwords and security → Smart Lock.

For maximum safety, we recommend combining the print. + PIN-Like a code:

• Use the scanner in the daytime.
• At night (when the sensor may not work) – PIN.

If you forgot. PIN-Restore access through Mi Account:

1. On the lock screen, click Forgot your password.
2. Log in to the Xiaomi account tied to your phone.
3. Follow the instructions for resetting the lock.

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On phones with an unlocked bootloader, the fingerprint scanner can be unstable, due to the change in cryptographic keys when running the firmware.

Frequently asked questions