Xiaomi: Why your fingerprint doesn’t work and how to fix it

When a Xiaomi smartphone stops responding to a finger touch, it can be taken by surprise at the most inopportune moment.The built-in fingerprint scanner, whether in the power button or under the screen, is a key element of biometric protection and usability. When this feature fails, the user is locked outside of his device or forced to constantly enter. PIN-code that annoys and takes time.

The causes can range from simple sensor contamination to serious hardware malfunctions of the plume or module. Often the problem lies in software that requires updating or resetting. In this article, we will discuss in detail why the fingerprint sensor stopped working, and provide a step-by-step algorithm for restoring functionality.

Before you bring your gadget to the service center, you need to rule out simple factors, and 80 percent of the time, the problem is solved by recalibrating or cleaning the scan area without disassembling the case, and let's go through all the scenarios that we can to get your data back quickly.

The main reasons for the failure of the fingerprint scanner

The first thing to look at is the physical condition of the sensor surface, and if you have a model with a scanner in the power button, it could have accumulated fat, sweat, or residues of a cover. For models with a subscreen scanner, the state of the protective glass is critical: thick or poor-quality films often block the optical signal.

The second common cause is software conflicts after a MIUI or HyperOS update. System bugs can disrupt the biometrics drivers, and the effects of static electricity or moisture that temporarily disorient the sensitive sensor should be considered.

• 🧐 Contamination of the scanner or screen surface with protective films.
• 🐛 Errors in the operation of the operating system after the update.
• 🔋 Overheating of the device affecting the operation of electronic components.
• 🔌 Problems with plume in recent repair or fall.

⚠️ Warning: If the phone has recently fallen or been hit, the problem may be hardware, in which case software methods may not help, and you will need a diagnosis in the service.

Basic settings and re-registration

Often, the system forgets or mishandles the stored fingerprints, especially if you were registering your finger in a hurry or in poor light, and the best solution is to delete the old data and re-register, following all the interface guidelines.

To do this, go to the Settings menu, select Passwords and Security, and then Unlock by fingerprint. Delete all saved profiles. It is important to wipe your finger and sensor with an alcohol wipe before starting the procedure to remove the fat film.

When you re-register, try to touch the scanner with different parts of your finger pad, changing the angle of inclination. The system will ask you to remove and apply your finger several times - don't ignore these steps. The more variations you write down, the more stable the biometric module will work in the future.

Don't try to register a print if your hands are sweaty or wet. Moisture distorts the pattern of papillary lines, and the sensor won't be able to create an accurate digital model. If the problem is in the gym or in the kitchen, it might be worth temporarily using a face unlock or a pattern lock.

Software solutions and resetting settings

If the physical cleanup didn't work, we'll move on to the software part, and sometimes the temporary security cache files get corrupted, and in this case, it helps to clean up the security application data or reset the biometrics settings, and it won't delete your personal photos or contacts, but it will return the factory settings of the scanner.

Try resetting all your phone settings to factory settings, but remember: this will delete all data.Be sure to back up your Xiaomi Cloud or your computer before doing so. Often, after a clean installation (without restoring the old backup settings), the scanner starts working as new.

Also worth checking for system updates. Xiaomi engineers regularly release patches that fix peripheral bugs. Go to Settings → About phone and click on MIUI. If there is a new version, install it.

Features of subscreen scanners

Owners of Xiaomi’s flagship and mid-budget models often face the peculiarities of optical scanners under the screen, they are sensitive to the brightness of ambient light and the type of protective coating. Unlike capacitive scanners in the button, it uses light that passes through the display matrix.

If you've recently changed glass or glued a hydrogel film, make sure they're certified to work with subscreen sensors. Conventional thick glass can block infrared radiation or visible light needed to read a finger pattern.

• 💡 Enable the “Sensitivity Enhancement” feature in the screen settings if available.
• 📱 Make sure that the screen brightness is not set to a minimum.
• 🛡️ Use only original or special protective glass.

⚠️ Warning: Some "privacy" glass completely blocks the work of the underscreen scanner. If after gluing the glass, the print stopped working, this is the expected behavior.

Another nuance is static electricity, and in winter or in dry rooms, the screen can accumulate a charge that interferes with reading correctly, and try swiping your finger across the screen or turning the display off and on before unlocking.

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Useful tip: If the underscreen scanner is slow, try selecting the “Speed Unlock” option (if available in your version of MIUI) in your fingerprint settings, sacrificing a bit of read radius for speed.

Hardware malfunctions and diagnostics

When software methods are exhausted, you have to talk about hardware, and the fingerprint module is a separate component connected to the motherboard by a plume, and if you fall, even without visible damage to the body, this plume could move away or get damaged.

It's hard to check the plume on your own without opening it, but you can do an indirect diagnosis. If the phone responds to a long press (there's a vibration, but the print doesn't read), the problem may be the calibration of the sensor, and if there's no reaction at all, there's a possibility of a break in contact.

In some cases, it helps to gently press the scanner area on the back (for models with the back panel) or in the button area. If the scanner comes alive after pressing, then contact is broken. But this is a temporary solution that requires repair.

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Diagnostics: If the scanner doesn’t work even in Safe Mode, then third-party applications have nothing to do with it, and the problem lies in the system or hardware.

It's also worth checking if the connector has oxidized. If the phone has come into contact with moisture, the contacts could have formed plaque. Cleaning the contacts with ultrasound or alcohol in the service often brings the device back to life without replacing parts.

Engineering menus and hidden tests

For advanced users, there is a way to check (hardware) through the engineering menu, which allows you to see if the system sees the sensor at all, type in the code # # #6484## to enter CIT mode (Customer Interaction Test).

In the menu that opens, find the item associated with Fingerprint or Touch. The system will offer a test: if after clicking on the scanner you see a change in values or hear an audible signal, then the module is working, and the problem is in the software. If the test does not pass, the module is defective.

The login code for the engineering menu: ##6484##


The Way to the Menu: CIT → Fingerprint Test → Start

Using this method is safe for data, but be careful: do not change the settings in other sections of the engineering menu if you are not sure about your actions.

⚠️ Note: Signing into the engineering menu does not guarantee 100% diagnostics. Some software failures of drivers can block even the test mode, creating a false impression of hardware failure».

Frequently Asked Questions (FAQ)