Why Xiaomi’s fingerprint scanner is hot – and what to do about it?

Introduction: When scanner heat is normal and when is a problem

Have you noticed that the area under the fingerprint scanner on your Xiaomi (whether it’s Redmi Note 12, POCO X5 or Xiaomi’s flagship 14) has become suspiciously warm? In most cases, light heating is normal, associated with the operation of the sensor. But if the temperature exceeds a comfortable 40°C, and the smartphone begins to brake or discharge quickly, it is a malfunction.

In this article, we will discuss 7 key reasons why the fingerprint scanner on Xiaomi is warming up – from harmless (for example, background data synchronization) to critical (damage to the plume or overheating of the processor). You will also learn how to diagnose the problem yourself and what to do to avoid damage to your phone. 13T or Redmi K60), where overheating of the sensor is often associated with improper operation OLED-matrix.

Before you panic, check if the heat is only during active use of the scanner (unlock, pay) or if the second is a deeper problem than it seems.

1. Software failures: when the software is to blame, not the hardware

In 60% of cases, overheating of the fingerprint scanner on Xiaomi is due to software errors, not hardware breakdowns.

🔄 Update Conflict: After installing the new version MIUI (especially beta versions) the sensor can operate in a reinforced mode, which leads to heating.
📱 Background processes: Applications with access to biometrics (bank programs, instant messengers) can constantly poll the scanner.
🔒 com.android.biometrics crash: This system service is responsible for the sensor's operation. If it freezes, the scanner will warm up even when it's in standby mode.

How do you check? Go to Settings → Apps → All apps → Show system and find BiometricService. If you have a high percentage in Battery Use, the problem is confirmed.

📊 Your Xiaomi is warming up with a fingerprint scanner after

MIUI updates

Installation of a new annex

Phone drop/hit

For no apparent reason.

Decision:

Reboot the phone – it will reset the background processes.
Clear the scanner cache: Settings → Passwords and security → Fingerprints → Delete fingerprint data (then add again).
If the problem appears after the update, roll back to the previous version of MIUI via Settings → About Phone → System Update → Three Points → Select the Service Pack.

💡

Before resetting your fingerprints, back up your Settings → Xiaomi Account → Backup – this will save your biometrics settings for quick recovery.

2.CPU overheating: why the scanner suffers "for company"

The fingerprint scanner on Xiaomi is often not warmed by itself, but by the general overheating of the smartphone. The processor (Snapdragon or Mediatek) and sensor are located close to the board, so the heat is transferred to the scanner area, this is especially noticeable in models with a metal body (for example, POCO F5 or Redmi K50 Gaming).

Causes of overheating of the processor:

🎮 Games or heavy apps: Genshin Impact, Call of Duty Mobile or even TikTok 4K load CPU/GPU.
🔋 Fast charging: When using power charging 67W+ (For example, in Xiaomi 12 Pro, the heat from the battery is transferred to neighboring components.
🌡️ High ambient temperature: If the phone is lying in direct sunlight or in the car in summer.

How do you check? Install a CPU Monitor or AIDA64 app and look at the CPU temperature, and if it's above 60°C, that's critical.

Processor temperature	Status.	Risk to the scanner
Up to 40°C.	Norma.	No.
40–50°C	Light heating	The scanner may be warm.
50–60°C	Overheating	The scanner is heating up strongly, there may be failures
Above 60°C.	Critical overheating	Risk of damage to sensor and battery

Decision:

Close the background applications through Settings → Applications → Launched.
Turn off fast charging in Settings → Battery → Fast charging (if the phone warms up while charging).
Use a cooling case or fan stand for games.

💡

If the processor is warming without load (for example, in standby mode), this may indicate damage to the thermal paste or a malfunction of the battery, in which case a diagnosis is required at the service center.

3. Underscreen scanner: why it warms up more than usual

Xiaomi models with a subscreen fingerprint scanner (for example, Xiaomi 13 Ultra, Redmi) K60 Pros are more likely to warm up because of the technology. OLED-It's a screen, and it uses the backlight of the display to scan it:

🔦 Additional heating from the matrix: OLED-The screen itself emits heat that is transferred to the scanner.
🔄 Enhanced processor work: More computing resources are required to process the fingerprint image through the screen.
📱 Sensitivity to brightness: At high screen brightness (>50%) the scanner can warm up more.

How do you check? Try to reduce the brightness of the screen to 30 to 40 percent and see if the scanner area is cooler, and if so, the problem is with the display settings.

Decision:

Turn off adaptive brightness in Settings → Display → Adaptive brightness.
Install a static wallpaper instead of live ones (they load the processor).
Update the scanner firmware via Settings → About Phone → System Update (sometimes Xiaomi releases patches to optimize subscreen sensors).

Why do underscreen scanners break down more often?

These sensors have a complex optical system that is sensitive to temperature changes, and frequent heating/cooling can disrupt the focus of the laser, leading to malfunctions or complete failure.

4. Physical damage: when repairs are not necessary

If the fingerprint scanner on your Xiaomi is warming up all the time, even after resetting, the cause may be hardware damage:

🔌 Sensor plume damaged: Often occurs after a phone drop or careless disassembly.
💧 Moisture: Even if the phone hasn’t sunk, condensation or high humidity can cause contacts to corrosion.
⚡ Short circuit: If the scanner not only warms but also “twitches” when touched, it’s a sign of power problems.

How do you diagnose?

⚠️ If the scanner is warmed to 50°C+ and the phone turns off or restarts, immediately disconnect it from charging and do not use - this can be a short circuit!

Perform a visual inspection:

Illuminate the flashlight on the scanner area - whether there are swellings or cracks.
Check if the screen is playing around the sensor (a sign of the plume detachment).
Connect your phone to your PC and check logs for errors via ADB: adb logcat | grep -i "fingerprint" If there are lines with E/Fingerprint errors - the sensor is faulty.

Decision:

If the phone is warranty, contact the Xiaomi service center (scanner repair is usually free).
If you don't have a warranty, check the cost of replacing the sensor. In mid-range Redmi models (like the Redmi Note 11), it costs between 1,500 and 3,000 to replace the sensor. ₽, in flagships (Xiaomi 13) - up to 5 000 ₽.

5. Non-original accessories: how charging and covers affect heating

Many users don't realize that poor-quality accessories can cause the fingerprint scanner to overheat.

⚡ Non-original chargers: Cheap power supplies (especially with AliExpress) can produce unstable voltages, causing the scanner controller to overheat.
📱 Tight covers: Silicone or armored cases degrade heat sink.In models POCO X3 or Redmi 9T This often causes local overheating.
🔋 Uncertified cables: Cables without Quick Charge support can cause power surges.

How do you check? Connect your phone to the original charger and check the scanner temperature in 10 minutes, and if it's normalized, the accessory problem.

Decision:

☑️ What to do to ensure that accessories do not heat the scanner

Use only original Xiaomi chargersRemove the case while chargingCheck the cable for damage (curves, melts)Do not use your phone while charging (especially for gaming)

Done: 0 / 4

If you play on your phone a lot, look for aluminum cases that are better at removing heat. For example, Spigen or Ringke cases for Xiaomi have special vents.

6. Viruses and malware: a hidden threat

Rarely, but accurately, some viruses may abuse access to the fingerprint scanner, making it work in a high-speed mode.

🕵️ Spyware: They can scan fingerprints to steal data.
💰 Cryptocurrency Miners: Viruses Use Phone Resources, Including Sensors, to Mine.
📱 Fake banking apps: They constantly poll the scanner to 'confirm transactions».

Install an antivirus (like Dr.Web or Kaspersky) and scan the system.

Go to Settings → Applications → Permissions → Biometrics.
Remove access to the scanner from unknown applications.
Check battery consumption in Settings → Battery → Battery use. Unknown high-consumption processes - red flag.

Decision:

Remove suspicious applications.
Reset your phone to factory settings (Settings → About Phone → Resetting).
Update MIUI to the latest version – Xiaomi regularly closes security vulnerabilities.

⚠️ Note: If the scanner stopped working after the virus was removed, it could mean that the malware damaged the system biometric files, in which case only flashing through Fastboot will help.

7. Battery wear: how the battery affects the scanner

Few people know, but a worn-out battery can be an indirect cause of overheating of the fingerprint scanner.

🔋 Increased resistance: Older batteries (health) < 80% heat up more, transferring heat to neighboring components.
⚡ Voltage spikes: Unstable power causes the scanner controller to work in enhanced mode.
📉 Accelerated discharge: The phone may include an energy-saving mode that mismanages sensors.

How do you check? Install the AccuBattery app and check the battery health. If it's below 80 percent, the battery needs to be replaced.

Decision:

Replace the battery at the service center (cost for Redmi Note 10 — ~2 000 ₽, Xiaomi 12 — ~3 500 ₽).
Turn off battery optimization for system applications in Settings → Battery → Battery Optimization.
Use the energy saving mode only at low charge.

If the scanner continues to warm after the battery is replaced, the problem lies deeper - perhaps in the power controller or motherboard.

FAQ: Frequent questions about heating a fingerprint scanner on Xiaomi

❓ The scanner only warms up when charging - that's normal?

Yes, light heating (up to 40°C) is normal when charging, especially if you use fast charging (33W+). But if the temperature is above 45°C, check the cable and power supply for originality.

❓ After the fall, the scanner began to warm up and not work well?

Most likely, the sensor plume or the module itself has been damaged. Don't try to disassemble the phone yourself, contact the service. If the phone is warranty, repairs will be free (without visible mechanical damage).

❓ Can the scanner overheat damage the phone?

Yes, if the temperature is constantly above 50.°C, this may result in: - Detachment of the scanner plume; - Damage OLED-matrix (in models with subscreen sensor); Accelerated wear of the battery. In critical overheating, the phone can turn off to protect the battery.

❓ Why does the scanner heat up at night when the phone is lying idle?

Probable reasons: 1) Background data synchronization (disable Settings → Accounts → Sync); 2) Viral software (check with antivirus); 3 System optimization (MIUI sometimes scans fingerprints to speed up unlocking). Try restarting your phone before going to bed.

❓ Can I use my phone if the scanner is warm?

If the heating is not accompanied by spontaneous reboots, the smell of burning or scanner failure, you can use the phone, but: - Avoid games and heavy applications; - Do not leave the phone on charging; - Monitor the temperature through AIDA64. If the scanner warms to 50 ° C +, contact the service.