Why the scanner on Xiaomi phone doesn’t work: a complete troubleshooting guide

Are you trying to unlock the Xiaomi Redmi Note 12 with a fingerprint, but the sensor is not responding? or is the camera stubbornly refusing to scan. QR-Mi Pay app code? scanner problems on Xiaomi smartphones (including Redmi sub-brands and POCO) According to service center statistics, up to 15 percent of calls are due to biometric sensor malfunctions or software failures of the camera module.

In this article, we will look at all possible causes, from simple sensor contamination to hardware breakdowns that require specialist intervention. You will learn how to diagnose a problem yourself, which settings to check first, and when it is time to carry the phone to the service. And for owners of older models (for example, Redmi 5 Plus or Mi A2), we have prepared separate recommendations – their scanners often suffer from wear and tear of flexible plumes after 3-4 years of use.

1. Software failures: when the software is to blame

In 70 percent of cases, the scanner stops working because of firmware errors or application conflicts, and let's start with the simplest one: checking system settings.

The first thing to do is:

• 🔄 Restart your phone. It's trivial, but it helps in 25 percent of cases -- especially if it crashed after you installed the update.
• 📱 Check if the energy saving mode is activated (in) MIUI It can turn off the biometric sensors. → Battery → Energy saving regime.
• 🔒 Make sure the scanner is not turned off in the security settings. → Passwords and security → Fingerprints (or facial recognition).

If the scanner still doesn’t work after the reboot, try clearing the cache for system applications:

1. Open Settings → Applications → Application Management.
2. Find Settings (system application) and select Storage → Clear cache.
3. Repeat for BiometricService (if listed).

2. Sensor contamination or damage

The fingerprint sensor on Xiaomi is often located under the screen (Mi 11, Redmi K50 models) or on the back (Redmi Note 8/9). In both cases, it is vulnerable to dust, moisture and mechanical damage.

How to check:

• 🔍 Look at the sensor for scratches, chips or greasy spots, and lighting up with a flashlight at an angle can help detect microcracks.
• 💧 If your phone has recently been in contact with water, don't use a scanner - oxidation of the contacts can make the problem worse. 24-48 hours in a dry place (for example, with silica gel).
• 🧴 Wipe the sensor with an alcohol wipe (at least 70% alcohol). Do not use abrasive materials!

⚠️ Note: On models with ultrasonic scanners (for example, Mi 10 Pro) you can not use alcohol - it damages the sensitive layer.

If the scanner still doesn’t respond after cleaning, try re-registering the fingerprint:

1. Remove all saved fingerprints in Settings → Passwords and security.
2. Add a new fingerprint, slightly changing the angle of the finger with each touch (this increases recognition accuracy).

Check the sensor for scratches.|Drink alcohol (not for ultrasound)|Remove and add the print again|Check the reaction of the other fingers.|Check the phone (if you have a phone)-->

3.Camera problems: why not scanning QR-code

If it's a scan, QR-codes (e.g. Mi Pay, Aliexpress or VC), the problem most often involves a camera module or application rights.On Xiaomi models with multiple cameras (e.g. Redmi Note 11 Pro)+) The main camera can be blocked by another process.

What to do:

• 📸 Check if the camera is being used by another app (like TikTok or Instagram in the background).Close all apps through Recent.
• 🔧 Give permissions for the scanning application: Settings → Annexes → [Title of the annex] → Permits → Camera.
• 🔄 Switch to another camera manually (if the app supports choice). For example, in Google Lens, you can choose the front camera if the main camera is not working.

If QR-codes are not scanned in all applications, run a camera test:

1. Open the standard Camera app.
2. Switch to Professional or Video mode.
3. Point at a bright object (like a lamp) if the image is blurry, with artifacts or black, the camera module is a problem.

4.Conflicts after the MIUI update

Xiaomi regularly releases updates for MIUI, but sometimes they break the biometric sensors. For example, after upgrading to MIUI 14, many users of the POCO X3 Pro complained about a broken face scanner due to a failure in the FaceUnlock service.

How to fix it:

• 📥 Check if the update has stopped. Go to Settings. → The phone. → Update the system and wait until the boot is complete (if there is an incomplete update).
• 🔙 Reverse to the previous version MIUI (If the crash happened immediately after the update:

1. Download the full firmware package (for example, from en.miui.com).


2. Rename the file to "update.zip" and place it in the root of the memory.




3. Go to Settings → About Phone → System Update → Three Dots → Select a firmware file.




4. Confirm the rollback.

⚠️ Attention: Firmware rollback erases all data on the phone unless you use Fastboot. pre-backup through Settings → Additionally. → Backup and reset.

If the rollback didn’t help or you don’t want to take risks, try resetting your security settings:

1. Go to Settings. → Passwords and security.
2. Select Reset Security Settings (may be called Remove All Credentials).
3. After restarting, reset the biometrics.

5. Hardware breakdowns: when you need to service

If the software methods didn't work, the problem is probably hardware. Here are the typical hardware malfunctions of the Xiaomi scanners:

• 🔌 The fingerprint sensor plume has gone (a common problem after falling or disassembling the phone).
• 💥 The scanner controller is damaged (for example, after moisture or short circuit).
• 🔋 Wear of flexible cable (relevant for models older than 3 years, for example, Redmi Note 7).
• 🔍 Failure of IR illumination (for face scanners, like in Mi 11 Lite).

How to diagnose:

• If the scanner stopped working after a fall or impact, it is almost certainly a mechanical problem.
• If the sensor reacts only with a strong press, the contacts of the plume may have moved away.
• If the scanner detects the fingerprint, but with a delay of > 2 seconds, the sensor or controller is worn out.

The cost of repairs in Xiaomi service centers (Moscow, 2026):

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Before going to the service, check if the warranty has expired. On the Xiaomi 2022-2026 model, the warranty for biometric sensors is 12 months (provided there is no mechanical damage).

6. Specific problems for different models

Some Xiaomi models have unique scanner diseases, and these are the most common ones.

• Redmi Note 8/8 Pro, Mi 9T: Failure of the motor of the retractable camera, which blocks the scanning QR-Symptom: the camera doesn't move or it makes a grin.
• POCO F3, Redmi K40: Overheating of the fingerprint sensor under the screen. The scanner turns off at a body temperature above 40°C.
• Mi 11 Ultra, Mi 11 Pro: Failure of the IR sensor for facial recognition after upgrading to Android 13.
• Redmi 9A/9C: Factory marriage of the fingerprint scanner (the sensor can "forget" the prints after the reboot).

For models with retractable camera (Mi) 9T, Redmi K20) non-working QR-scan:

1. Try to manually push the camera (carefully pulling the upper part of the body).
2. If the camera is not fixed, do not try to push it by force - this can damage the mechanism.
3. Use an external scanning app (like Gamma Play’s QR & Barcode Scanner) that can work with the front camera.

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In the models with AMOLED-screens (e.g. Xiaomi) 12T) The underscreen fingerprint scanner may not work well in bright sunlight, in which case try scanning your finger in the shade or reducing the screen brightness to 50%.

7. Alternative methods of unlocking and scanning

If the scanner refuses to work, and urgently need to unlock the phone or scan QR-Code, use alternative methods:

• 🔐 Password/pattern lock: Always set up a backup unlock method in Settings → Passwords and security.
• 📷 External scanners QR: If the phone’s camera is not working, take a photo of the code with another device and enter the data manually.
• 💻 Mi Unlock Tool: to unlock the bootloader (if the phone is locked after a failed firmware!
• 📱 Safe Mode: boot your phone in Safe Mode (hold the power button) → Reboot to Safe Mode to check if a third-party app is to blame.

For Xiaomi NFC owners (like Redmi Note 11 NFC): If the payment tag scan doesn’t work, try:

1. Reconfigure Mi Pay or Google Pay.
2. Check if NFC conflicts with other wireless modules (turn off Bluetooth and Wi-Fi during the test).
3. Update the firmware of the NFC module through Settings → Connections → NFC → Update (if available).

FAQ: Frequent questions about Xiaomi scanners