Why Xiaomi’s fingerprint scanner doesn’t work: a full analysis of the causes and solutions

The fingerprint scanner on Xiaomi smartphones is one of the most convenient ways to unlock, but sometimes it stops working for no apparent reason: the device does not recognize the registered finger, the sensor does not respond to touch at all, then after the system update, the function disappears from the settings. In 80% of cases, the problem is solved by software methods, but in some situations, hardware failure is to blame.

In this article, we’ll look at all the possible reasons why a fingerprint might not work on Redmi, POCO Or Mi, from the commonplace contamination of the sensor to the firmware failures, you'll learn how to diagnose a malfunction, which settings to check first, and when to carry the phone to the service center. A2) We have prepared separate recommendations - their sensors often fail due to wear and tear.

Before you go to radical measures (like factory resets), try simple steps like rebooting your phone, cleaning your sensor, or re-registering your fingerprint, which is 30 percent of the time enough to get functionality back. If the problem persists, read on.

1. Pollution or damage to the fingerprint sensor

The most obvious but often overlooked reason is physical contamination of the sensor, and the fingerprint sensor on Xiaomi may stop working because of:

• 🧴 Fat marks from the fingers (especially after eating or using cream)
• 💦 Ingestion of moisture or condensate (relevant for wet rooms)
• 🧂 Fine dust or sand (if the phone is often lying on a desk or in your pocket)
• 🩹 Scratching or chipping on the sensor glass (often after falls)

On models with an optical scanner under the screen (for example, Xiaomi 12 Pro or Redmi). K50) The problem gets worse: the contamination builds up under the protective glass, and it's harder to see. Check the sensor for the lumen - if you see divorces or cloudy spots, you will need to clean up.

How to clean the sensor:

1. Turn off the phone and get it out. SIM-card (if the sensor is on the back panel).
2. Wet the cotton swab in isopropyl alcohol (at least 70%) or a special liquid to clean the screens.
3. Gently wipe the surface of the sensor without pressing, then let it dry. 2-3 minute.
4. For optical scanners under the screen, use a soft microfiber (as for glasses).

⚠️ Warning: Do not use abrasive materials (cloth wipes, paper towels) or aggressive solvents (acetone, gasoline) that will damage the sensor's protective coating.

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If the sensor still does not work after cleaning, try to register the fingerprint of the other finger - sometimes the sensor "forgets" old patterns due to accumulated errors.

2. Software glitches: from updates to application conflicts

Most often, the fingerprint scanner stops working after:

• 📱 Updates MIUI (especially in beta versions)
• 🔄 Resetting settings or flashing
• 🤖 Installation of third-party launchers or Magisk modules
• 🛡️ Activation of "Developer Mode" with changes in animation

V MIUI 14 and later, there is a bug that, after the update, disappears the "fingerprint" item in the security settings, which is due to incorrect migration of data from the old version:

1. Open the Settings. → The phone.
2. Click 7 times on the MIUI version to activate the developer mode.
3. Back to Settings → Additionally. → For developers.
4. Find the option Reset fingerprint settings and confirm the action.

If the problem occurs after installing third-party apps (such as Xposed or Tasker), try:

adb shell pm uninstall -k --user 0 com.example.conflictingapp

Replace com.example.conflictingapp with a conflicting application package (you can find out through Settings). → Annexes).

3. Incorrect registration of a fingerprint or system limitations

Even if the sensor is in good condition, the scanner may not work because of a pattern that is not properly stored.

• 👆 The finger was pressed at different angles (the system retains only part of the print).
• 💦 The hands were wet or dirty.
• 📱 The phone vibrates or moves during the scan.
• 🔋 Battery charge was below 15% (MIUI block the registration).

How to properly re-register the fingerprint:

Remove old prints in Settings → Passwords and security → Fingerprint.

Select your finger and follow the instructions on the screen.

Press your finger tightly but without pressing, lifting it after each signal.

Register the same finger. 2-3 at different angles for reliability

Check the scanner in different conditions (in bright light, in the dark)

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In some models (for example, POCO X3 Pro or Redmi 9T) There's a limit: maximum 5 prints. If you add more, the system can block the scan. Also check if Guest Mode or Second Space is activated, they don't work.

⚠️ Note: If you register for a "failed to add a fingerprint" error, try turning off Adaptive Brightness in the screen settings. In rare cases, the sensor conflicts with the light sensor.

4. Hardware breakdowns: when to carry in the service

If none of the software methods worked, the problem may be a physical malfunction of the sensor or the plume, and you can recognize the hardware breakdown by the following signs:

On models with an ultrasonic sensor (for example, Xiaomi Mix 4), breakdowns are less common, but they are more difficult to repair. ADB), He'll have to be replaced.

Cost of repairs in service centers:

• 🔧 Replacement of sensor plume: from 800 to 1500 rubles.
• 📱 Replacement of the sensor itself: from 1500 to 3000 rubles (depending on the model).
• 🔌 Diagnostics + intersection of contacts: from 1000 rubles.

5. Conflicts with firmware and custom recovery

If you have installed custom firmware (e.g. LineageOS, Pixel Experience) or modified recovery (TWRP), The fingerprint scanner may not work because of:

• 📦 Absence of drivers for the sensor in the assembly.
• 🔑 Incompatibility of the kernel with the hardware platform.
• 🔄 Conflict between vendor and system partitions.

Solutions for custom firmware:

1. Make sure the firmware supports your model (check out the XDA Developers or 4PDA forum).
2. Refresh the seller section from stock firmware: fastboot flash vendor vendor.img
3. Try the kernel with Fingerprint support HAL (For example, Kernelsu for new models).

On certain devices (e.g, POCO F1) After the firmware, you need to unlock the bootloader again, otherwise the sensor will not be determined:

1. Activate Fastboot Mode (Lock Power) + Vol Down).
2. Connect your phone to your PC and execute: fastboot flashing unlock
3. Confirm the unlock on the phone screen.

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If the scanner stopped working after firmware, first check logs through adb logcat. | grep -i FingerprintService: vendor.qti.hardware.biometrics.fingerprint@2.1-service Not found indicates absence HAL-module.

6. Features of working on old Xiaomi models

Owners of Xiaomi smartphones 2017-2019 release (for example, Redmi Note 5, Mi) A1, Mi 8) often encounter wear and tear of the sensor or deterioration of its operation:

• 🕒 Sensor degradation (especially on capacitive sensors).
• 🔋 Battery wear, which is why the sensor does not receive enough power.
• 📉 Outdated firmware that does not have optimizations for modern applications.

For older models, there are several specific solutions:

• 🔄 Back on. MIUI 10 or MIUI 11 – Newer versions may not support older sensors.
• 🔋 Replace the battery (if the capacity has dropped below 70%, the sensor can shut down when the charge is low).
• 🛠️ Check the sensor contacts on the board - over time they oxidize.

On the Redmi Note. 4X And similar models sometimes help to turn off energy saving for security systems:

1. Go to Settings → Battery and Performance → Application Power Management.
2. Find System Settings or SecurityCenter.
3. Choose No Limits.

On Mi. A2 (Android One after upgrading to Android 10+ The fingerprint scanner is shut down because there's no driver, and the only solution is to flash through the custom kernel with support. FPC1020 (sensor).

External factors: covers, film, temperature

Sometimes the problem isn't with the phone, it's with the outside.

• 📱 Case or bumper – if it is too thick or closes the sensor, the scanner will not work, POCO M3).
• 🧊 Ambient temperature - at a temperature below 0°C or higher than 40°C sensor can be turned off for protection.
• 🔋 Protective glass or film – if it is glued crooked or too thick, the optical scanner will not recognize the fingerprint.
• 💍 Jewelry on the fingers (rings, nails) - they distort the pattern of the fingerprint.

If you use a magnetic case (for example, for wireless charging), it can interfere with the sensor. Try to remove the case and check the scanner.

On models with an ultrasonic sensor (such as the Xiaomi Mi 11 Ultra), the problem may be in the silicone case - it absorbs ultrasonic waves. Replace it with plastic or leather.

Frequently asked questions