Why the fingerprint doesn’t work on Xiaomi Redmi 9: 10 reasons and step-by-step solutions

The Xiaomi Redmi 9 fingerprint scanner is a convenient feature for quick unlocking, but sometimes it stops working for no apparent reason. It doesn't recognize your finger, the sensor doesn't respond to touch at all. In this article, we'll look at all the possible causes, from simple sensor contamination to software failures in the firmware, and give step-by-step instructions for restoring the scanner.

It is important to understand that the problem can be both hardware (physical breakdown of the sensor) and software (failure to perform the task). MIUI We will not advise you to immediately bring the phone to the service - in 80% of cases, the malfunction can be fixed yourself, but if after all the manipulations the scanner has not worked, this is an occasion to think about diagnostics in an authorized Xiaomi center.

This article is relevant for all Redmi 9 versions (including Redmi). 9A, Redmi 9C, Redmi 9T), Because they use similar fingerprint sensors, some of the solutions are also suitable for other Xiaomi smartphones based on the same fingerprint. MIUI 12–14.

1. Pollution or damage to the fingerprint sensor

The most obvious but often overlooked cause is physical contamination of the sensor, the fingerprint sensor on the Redmi 9 is located on the back (or under the screen in some versions) and is in constant contact with skin, dust and fat, which over time leads to plaque that interferes with correct reading.

How to check:

• 🔍 Examine the sensor in good lighting – if you see greasy plaque, scratches or dust, it needs to be cleaned.
• 🧴 Wipe the sensor with a soft, lilaless cloth soaked in alcohol solution (at least 70!
• 💧 Avoid moisture – if the sensor is wet, wait for the full drying (minimum 30 minutes).

If the scanner is not working after cleaning, check it for mechanical damage:

• 🔧 Is the sensor cracked or chipped? That's a sure sign of hardware breakdown.
• 📱 Check if the sensor responds to touch with at least vibration or backlighting (if any).

⚠️ Warning: Never use acetone, gasoline or other aggressive solvents to clean the sensor – they can damage the protective coating of the sensor and permanently disable it.

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If the sensor is located under the screen (as in the Redmi 9 Pro), clean it only with a dry microfiber wipe.

2.Incorrectly added fingerprint

Often the problem is not with the sensor itself, but with a fingerprint that is not properly stored, for example, if you add a finger at the wrong angle, with dirty hands, or swipe through the sensor too quickly, the system may not recognize it later.

How to overwrite a print:

1. Open Settings → Passwords and Security → Fingerprints.
2. Delete all saved prints (click on each and select Delete).
3. Add the print again by following the instructions on the screen: 👆 Hold your finger at the same angle as you will unlock your phone. 🧼 Hands should be clean and dry. 🔄 Repeat the process 2-3 times for one finger to improve recognition.

If the system produces an error when adding a fingerprint (e.g., “Failure to save”), this may indicate:

• 📱 Failure to work MIUI — Try restarting your phone.
• 🔋 Low battery (less than 15%) – connect the charger and try again.

Make sure your hands are clean and dry.|

Watch the angle of finger application|

Add the same finger 2-3 times for reliability|

Do not interrupt the preservation process.

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3. Programmatic failures in MIUI

The fingerprint scanner is closely integrated with the firmware MIUI, And any errors in the system can cause it to fail:

• 📲 Firmware updates (especially if the update is interrupted).
• 🔄 Custom installations ROM or modified versions MIUI.
• 🧩 Conflict with applications requesting access to biometric data.

How to fix it:

Method 1: Reboot the phone

It's trivial, but it works 30 percent of the time. Hold the power button for 10 seconds until the phone turns off, then turn it on again.

Method 2: Cleaning the cache of the system

Go to Settings. → The phone. → Memory. → Clean up and select Clear cache.This won't delete your data, but can eliminate temporary errors.

Method 3: Resetting security settings

If previous methods didn’t help, try resetting your security settings (this will remove all fingerprints and passwords):

1. Go to Settings. → Passwords and security.
2. Select “Resetting Security Settings”.
3. Confirm the action and restart the phone.

⚠️ Note: After resetting the security settings, you will need to reconfigure the unlocking on PIN-Your fingerprints will also be deleted.

Updated firmware.|

Installation of a new application|

Ronili/phone hit|

Nothing unusual.|Other-->

4. Conflict with applications or services

Some applications (especially banking, messengers, or data protection software) can block access to the fingerprint scanner.

• 🔒 Permission conflict – for example, two applications simultaneously try to use biometrics.
• 🛡️ Active antivirus or VPN, which blocks access to system functions.
• 📱 Errors in the cache of applications that work with fingerprints (for example, Google Pay or Mi Wallet).

How to identify and resolve conflict:

Step 1: Verifying Application Permissions

Go to Settings. → Annexes → Permits → Other permits → Using fingerprints and see which programs have access to the scanner. disable permissions for suspicious apps.

Step 2: Cleaning up the data of problematic applications

If the scanner stopped working after installing a particular application (such as a banking application), try:

1. Open Settings → Annexes → [Title of the programme].
2. Click on “Clear Cache” and “Clear Data”.
3. Reboot the phone.

Step 3: Safe Mode

Load your phone in Safe Mode (hold the power button) → long-press on "Switch off» → «Safe Mode. If this mode is running, it means that the problem is in one of the installed applications. Uninstall the newly installed programs one at a time to identify the culprit.

5. Damage to firmware or system files

If the fingerprint scanner stopped working after the update MIUI Or custom firmware installations, the problem may be in corrupted system files, which is especially true for Redmi 9, as some builds are not available. MIUI This device contains bugs.

Signs of firmware damage:

• 📱 The scanner does not respond at all (no vibration, backlights).
• 🔄 There is no “fingerprint” section in the settings».
• 🚨 Error: Fingerprint service stopped».

Decisions:

Method 1: Update the firmware

Check for updates in Settings → The phone. → Update system if a new version is available MIUI, You can install it. Often, in fresh builds, they fix biometric bugs.

Method 2: Reset to factory settings

If the update doesn’t work, do a hard reset (all data will be deleted!):

1. Make a backup copy of important data.
2. Go to Settings → About Phone → Resetting → Resetting all settings.
3. Confirm the action and wait for the reboot.

⚠️ Warning: Once reset, the phone will return to the factory firmware, and if the problem was caused by custom recovery or root rights, they will also have to be reinstalled.

Method 3: Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fastboot Fast Fastboot Fast Fastboot Fast Fastboot Fastboot Fast Fastboot Fast Fastboot Fast Fastboot Fast Fast Fastboot Fastboot Fast

If the reset didn't help, the biometric driver section might be damaged, and then a full Fastboot flashing will help.

1. Download the official firmware for Redmi 9 from Xiaomi website.
2. Unpack the archive and connect the phone to your PC in Fastboot mode (clip Volume Down + Power when the phone is off).
3. Launch the file. flash_all.bat (For Windows, use the command: fastboot flash all

6. Hardware malfunctions: when without service can not do

If all the software methods have been tried and the fingerprint scanner on Redmi 9 still doesn't work, it's probably a hardware problem.

How to check if the problem is hardware:

• 🔧 Check if the sensor responds to touch with any finger (if not, it is likely to be a physical breakdown).
• 📱 Connect your phone to your PC and check logs through ADB (adb logcat | grep -i If you have any errors like Fingerprint. HAL Failed, this confirms hardware malfunction.
• 🔍 Inspect the sensor for bloating, cracking, or traces of oxidation.

If you suspect a hardware breakdown, don’t try to disassemble the phone yourself – the fingerprint sensor on the Redmi 9 is soldered to the plume, and its replacement requires soldering equipment. Contact the authorized Xiaomi service – this guarantees the use of original parts and the preservation of warranty (if it is still valid).

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If the phone is warranty, don't open it yourself! Any traces of parsing will void Xiaomi's warranty obligations.

7. Alternative ways to unlock if the scanner is not working

While you are looking for a solution or waiting for a repair, you can use alternative methods to unlock Redmi 9:

• 🔐 PIN-A code or pattern lock is the most reliable option, but less convenient.
• 👤 Facial recognition (if supported by your model) is included in Settings → Passwords and security → Facial recognition.
• 📱 Smart Lock – Automatically unlock in trusted places (such as at home) → Passwords and security → Smart Lock.
• 🔑 External fingerprint scanner (through the USB-C Bluetooth – suitable for corporate use.

If you use facial recognition, consider its disadvantages:

• ❌ Works worse in the dark or when changing appearance (glasses, beard).
• ❌ Less secure than a print (you can fool a photo).
• ❌ Does not work for authorization in banking applications.

For maximum safety, we recommend combining PIN-code + facial recognition or use a hardware token (e.g., YubiKey) for important accounts.

8.Prevention: How to avoid scanner problems in the future

To ensure that the fingerprint scanner on Xiaomi Redmi 9 works stably, follow these recommendations:

• 🧴 Clean the sensor regularly with a soft cloth (1 time per week).
• 🚫 Avoid pressing the sensor hard – it can damage your contacts.
• 🔋 Do not use the scanner when the battery is low (less than 10%).
• 📱 Update the firmware MIUI until the last stable version.
• 🔒 Do not install unofficial firmware without a backup.
• 💧 Avoid getting moisture or dust under the sensor.

Also useful:

• 📌 Add a spare print (such as the index finger of the other hand) in case the main one stops reading.
• 🔄 Re-write the prints every 3-6 months, as the skin on the fingers changes over time.
• 🛡️ Use cases without protrusions in the sensor area to avoid accidental pressing.

Important: If you drop your phone frequently or work in high humidity environments (such as the kitchen or the gym), consider using a protective film for a fingerprint sensor that prevents dirt and moisture from getting in, but can slightly degrade the sensor sensitivity.

Once a week |

Once a month |

Only when you stop working.|

Never cleaned.-->

FAQ: Frequent Questions About the Redmi Fingerprint Scanner 9