Why the fingerprint works poorly on Xiaomi: reasons and how to fix

The fingerprint scanner on Xiaomi smartphones should provide instant unlocking and reliable data protection. However, many users face a situation where the sensor stops recognizing the fingerprint, works with delays or refuses to respond at all, the problem can manifest itself in various ways, from accidental failures to complete failure of the system.

In this article, we will discuss 7 Main reasons why Xiaomi fingerprint scanner (including Redmi Note models) 10/11/12, POCO X3/X4/X5, Mi 11/12/13) It can work poorly, and we'll give you step-by-step instructions for diagnosing and troubleshooting, and we'll focus on software failures, physical damage, and firmware. MIUI, often left unattended.

If your smartphone suddenly doesn't recognize a fingerprint, don't rush to take it to the service center. In 80% of cases, you can solve the problem yourself - just know where to look for the root of evil.

1. Pollution of the sensor or protective glass

The most common, but common, reason is that dirt, fat, or moisture hit the surface of the scanner.

• 🔹 Built-in screen (ultrasonographic, like on Mi 11 Ultra or Redmi) K50 Pro)
• 🔹 A separate button (on older models like the Redmi Note 8 Pro)
• 🔹 Located on the side panel (as on the POCO F4 Xiaomi 12T)

In the first case, the problem is often a protective film or glass that interferes with proper scanning, in the second and third case, the accumulation of dust or potassium fat marks on the sensor itself.

What to do:

1. Wipe the sensor with a soft lilaless napkin dipped in alcohol (at least 70%).
2. If the scanner is built into the screen, remove the protective film and check the work without it.
3. For side sensors, use a toothpick with cotton wool to gently clean the recess.

⚠️ Note: Do not use abrasive materials (such as paper wipes) – they can scratch the sensor!

Damage to the sensor or plume

If the scanner stopped working after falling, hitting or disassembling the phone, there is a high probability of physical damage.

• 🛠️ Sensor plume (removes in case of careless disassembly)
• 💥 The sensor itself (cracks when hit hard)
• 🔌 Contacts on the motherboard (oxidized when moisture enters)

Symptoms of physical breakdown:

• 🔴 The sensor does not respond at all (no vibration/backlighting when touched).
• 🔴 The phone freezes when you try to add a new print.
• 🔴 There is no option in the security menu to add a fingerprint.

How to check:

1. Connect your phone to your PC and start the Android Debug Bridge (ADB).
2. Enter the command: adb shell dumpsys fingerprint If the answer has mHalDevice = null, the sensor is not determined by the system.

⚠️ If the sensor is not recognized at iron level, it will cost 1,500-4000 to replace it. ₽ (On Xiaomi 13 Pro or Redmi K60 Ultrasonographic scanner repair may require replacement of the entire display!

3. Failure of firmware or MIUI

Software errors are the second most common cause of a failed scanner, especially for devices on MIUI 13/14, where biometric bugs occur after:

• 📱 Updates by air (OTA)
• 🔄 Resetting to factory settings
• 🛠️ Custom firmware installations (e.g. LineageOS or Pixel Experience)

Typical symptoms:

• 🔄 The scanner works over and over again or requires several attempts.
• 🔄 When you add a fingerprint, you get an error and you can't save the print.
• 🔄 In system logs (Settings) → The phone. → Error log) Fingerprint Service failure records appear.

Decisions:

1. Cache cleaning: Settings → Annexes → Application management → Three points (⋮) → Show system-based → Biometry → Clear the cache
2. Reset your biometrics settings: Settings → Passwords and security → Fingerprints → Delete all fingerprints After that, restart your phone and add the fingerprint again.
3. Firmware rollback (if the problem has occurred after the update) To do this, download the old version of MIUI from miuirom.org and run through Fastboot.

4. Conflict with security software or root access

If you have installed antivirus, VPN or obtained root rights, the fingerprint scanner may be blocked because of:

• 🔒 Changes to the file /system/build.prop (For example, after modification to circumvent regional restrictions).
• 🛡️ Application activity like Magisk, Xposed or LSPosed.
• 🔍 Antivirus works (such as Avast or Kaspersky) that block access to biometric data.

How to check:

1. Run your phone in Safe Mode (hold the power button → long tap on "Switch off" → "Reboot in Safe Mode"). If the scanner is working, it's third-party software that's to blame.
2. Check logs via ADB: adb logcat | grep -i fingerprint Look for lines with denied or permission.

Decisions:

• 🔹 Remove newly installed antiviruses or VPN.
• 🔹 In Magisk, disable modules associated with modification of system services.
• 🔹 Restore the original build.prop through TWRP.

💡

If the scanner stopped working after the Magisk update, try flashing the Fingerprint Fix for MIUI module from the Magisk repository.

5.Problems with battery or sensor power

Few people know, but the fingerprint scanner on Xiaomi requires stable power. If the battery is discharged below 15% or there are problems with the power controller, the sensor can:

• 🔋 Disconnect arbitrarily (especially in the cold).
• 🔋 Work with a delay of up to 2-3 seconds.
• 🔋 Sensor fails to respond to error.

How to diagnose:

Critical case: if the scanner stopped working after the battery was replaced, it is likely that the master damaged the sensor plume or did not connect it back, in which case a redisassembly is required.

6. Misregistration of the fingerprint

It seems easy to add a fingerprint, but many users make mistakes that make the scannerlater unstable.

• 👆 Too fast touch (the sensor does not have time to read the full image).
• 🧼 Wet or dirty fingers when registering.
• 🔄 Use only a part of your finger (for example, only the pads).

How to add a fingerprint correctly:

1. Remove all saved fingerprints to Settings → Passwords and Security → Fingerprints.
2. Wipe your finger and sensor with a dry wipe.
3. When registering, press your finger tightly and raise it only after vibration.
4. Add the same finger 2-3 times at different angles (this increases recognition accuracy).

For models with ultrasonographic scanner (for example, Xiaomi 13 Ultra):

• 🔹 Register the print in good lighting (the sensor uses light to scan the print).
• 🔹 Don’t press too hard – a light touch is enough.

💡

In the models with AMOLED-screens (e.g. Redmi) K50 Pro) the scanner may be worse at low display brightness. Before registering the fingerprint, increase the brightness to 70% or more.

7. Hardware limitations of older models

If you have Xiaomi releases from 2018-2020 (for example, Redmi Note 7, Mi 9, POCO F1), the problem may be in the outdated sensor.

• 🕒 Sensitivity is reduced (especially on mechanical buttons).
• 🔋 Contacts between the sensor and the motherboard wear out.
• 📉 The firmware no longer supports old drivers (relevant to the MIUI 14+).

What can be done:

• 🔹 Install custom software (like LineageOS 20) where older sensors are better supported.
• 🔹 Use alternative methods of unlocking (PIN, graphical).
• 🔹 If the sensor is built into the button, try disassembling the phone and cleaning the contacts (requires experience!).

For models older than 5 years (e.g. Redmi 4X, Mi A1), scanner repair is often impractical - it's cheaper to buy a new phone.

FAQ: Frequent questions about the fingerprint scanner on Xiaomi