Xiaomi’s smartphone screen suddenly became dim, the brightness regulator does not respond to changes, or autobrightness works unpredictable? These problems are familiar to many users of devices on MIUI – from budget Redmi to flagship Xiaomi 13/14. In 80% of cases, software failures are to blame, but sometimes the root of the evil lies in hardware malfunctions or incorrect system settings.
In this article, we’ll look at 7 proven ways to regain control of screen brightness, from the elementary reboot to hidden engineering menus. You’ll learn how to bypass automatic adjustment bugs, why the screen can spontaneously dim when the battery is low, and what to do if the brightness slider in the settings is fixed at the same level and does not move. All instructions are relevant for MIUI 12/13/14 and newer versions, including HyperOS.
Before you start taking drastic measures (like resetting), check the obvious: whether you have read mode (Settings → Display → Read Mode) or energy saving (Settings → Battery → Power Saving Mode), which often block the brightness regulator from working properly.
1. Basic checks: what to do before resetting
Start with simple actions – they help in 60% of cases and do not require deep technical knowledge. Most often, screen brightness on Xiaomi is lost due to temporary system failures or application conflicts.
The first thing you need to do is reboot your smartphone. Press the power button, select Reboot, and wait until it's fully powered, and if the brightness returns to normal after that, the problem was with the stalled MIUI Display Service.
- 🔄 Reboot: eliminates temporary crashes of display drivers. Helps if the screen fades after updating or installing the application.
- 🔋 Battery test: below 15%, Xiaomi automatically lowers brightness to save energy.Plug in the charge and see if the slider returns to normal.
- 🛡️ Power Saving Disconnect: Super Power Saving or Ultra Energy Saving modes block brightness adjustment. Turn them off in Settings → Battery.
- 📱 Safe Mode Test: If a third-party app is to blame, the brightness will work normally in safe mode. To enter, press the power button. → long-tail → Safe regime.
If the basics didn't work, go to deeper settings, but first check if you have adaptive brightness on, which often conflicts with manual adjustment.
- Open the Settings → Display.
- Find Adaptive Brightness (or Auto Brightness in older versions of MIUI).
- Turn off the slider and check if it is possible to change the brightness manually.
2. Reset display settings: return factory settings
If the dimmer doesn't respond to changes, or if the screen stays dim regardless of settings, try resetting the display settings. This doesn't affect personal data, but it will return all screen settings to factory values.
Instructions for MIUI 14/HyperOS:
- Go to Settings → Display.
- Slip on the three points in the upper right corner (or additionally).
- Select Reset Display settings.
- Confirm the action.
After the reset, check:
- 🔦 Does the brightness slider work in the notification panel.
- 🌞 Has not automatically activated adaptive brightness.
- 🎨 Are the color temperature settings (Settings) wrong? → Display. → Color mode).
If the reset didn’t work, the problem could be in corrupted system files, in which case resetting all settings (see Section 5) or flashing it will help.
💡
Before resetting your display settings, take a screenshot of the current settings (color mode, resolutions, refresh rates) to help you quickly restore your usual settings.
3. Adaptive brightness setting: why it breaks and how to fix
Adaptive brightness (or autobrightness) on Xiaomi often works incorrectly: the screen becomes too dim indoors or blinds outdoors, due to inaccurate light sensor data or failures in the MIUI algorithms.
To calibrate the autobrightness:
- Turn off adaptive brightness in Settings → Display.
- Manually set a comfortable brightness level (for example, 50%).
- Turn on the adaptive brightness back.
- Go to Settings → Special features → Configure the light sensor (if there is a point in your firmware).
- Follow the instructions on the screen to calibrate the sensor.
If the light sensor is damaged (for example, after a phone drops), the autobrightness will work unpredictably.
- Open the Phone app and dial ##6484## (sensor test code).
- Select the Light Sensor Test from the menu.
- Cover the sensor (usually located next to the front camera) with your finger — the value should drop sharply. Remove the finger — the value should rise.
What if the #6484## code doesn’t work?
| The problem with autobrightness | Possible cause | Decision |
|---|---|---|
| The screen is too dim in the room. | The light sensor is contaminated or damaged | Wipe the sensor with a soft cloth or calibrate manually |
| Brightness jumps for no reason. | Conflict with MIUI shell or application | Update the firmware or reset the display settings |
| Auto-brightness not switched on | Disabled in settings or system failure | Check the display settings or perform a reset |
| The screen is blinding in the street | Incorrect threshold values of the sensor | Turn off autobrightness and adjust manually |
4. Engineering menu: hidden brightness settings
If standard methods don't work, you can try changing the brightness parameters through the engineering menu, which is a risky method - the wrong settings can make things worse, so proceed carefully.
Instructions for entering the engineering menu:
- Open the Phone app.
- Enter the code ##36446337## (for MIUI) or #4636## (universal).
- Select Hardware Testing → Sensors → Light Sensor.
- Check the current light sensor values.
For manual brightness adjustment:
- In the engineering menu, select Display.
- Find the Brightness Mode and Manual Brightness options.
- Set Brightness Mode to 0 (manual adjustment) or 1 (automatic).
- In Manual Brightness, set a value from 0 (minimum) to 255 (maximum).
⚠️ Attention: Changing the settings in the engineering menu can lead to unstable screen operation. Do not change the values unless you are sure of their purpose.
If the engineering menu is not available (the code is not working), try an alternative method:
adb shell settings put system screen_brightness 150This command (introduced via ADB on PC) will set the brightness to 150 (out of 255 possible). To use ADB, you need to enable USB Debugging in Settings → About Phone → MIUI Version (tap 7 times) → Additional → For developers.
5. Reset to factory settings: a last resort
If none of the methods worked, you'll have a complete reset, which will delete all the data from your phone, so back up first:
- 📱 Contact and SMS: Export through Settings → Google → Backup.
- 📷 Photos and videos: copy to PC or cloud (Google Photos, Mi Cloud).
- 🔑 Passwords: Save data from accounts in the password manager.
Resetting instructions:
- Open Settings → About Phone → Backup and Reset.
- Select Settings Reset.
- Confirm the action and wait for the reboot.
After discharge:
- 🔧 Adjust the brightness manually (Settings) → Display).
- 🚫 Do not restore settings from backup – this can return the problem.
- 🔄 Update the firmware to the latest version (Settings) → Updating the system).
⚠️ Note: Some Xiaomi models (e.g. Redmi Note 10 Pro) may have their light sensor calibrated after reset. If the autobrightness is not working properly again, recalibrate (see Section 3).
Make a backup copy of your contacts and SMS|Save photos and videos on PC/cloud|Record passwords from important accounts|Unplug your Xiaomi account (if you sell your phone)|Check the battery level (minimum 50%)-->
6. Hardware problems: when it is not the fault of software
If the software methods didn’t help, the problem could be in the hardware:
- 💡 Screen illumination: Over time, it degrades, causing the screen to become dim even at maximum brightness.
- 📱 Display plume: After falling or repairing, it may be damaged, leading to flickering or incorrect brightness.
- 🔋 Power controller: in case of malfunction limits the supply of voltage to the backlight.
- 🌡️ Light sensor: If contaminated or disconnected, autobrightness doesn't work properly.
How to diagnose a hardware malfunction:
- Check if the brightness changes when you boot in safe mode. If so, the problem is in the software.
- Connect your phone to charging – if the brightness temporarily normalizes, the power controller is to blame.
- Illuminate the flashlight on the light sensor – if the brightness does not respond, the sensor is defective.
- Check the screen for flickering in a dark room (set minimum brightness). The flicker indicates problems with the backlight or plume.
If you suspect a hardware malfunction:
- 🛠️ Contact the Xiaomi service center (warranty repair is possible in case of factory marriage).
- 💰 The cost of replacing the lighting or plume - from 1500 to 5000 rubles (depending on the model).
- ⚠️ Do not attempt repair yourself - risk damaging screen or motherboard.
💡
If the brightness of the screen is not adjusted even after resetting, and the parameters do not change in the engineering menu, there is a 90% probability that the problem is hardware.
7. firmware update: fixing MIUI bugs
Many brightness issues on Xiaomi are related to bugs in specific versions of MIUI. For example, MIUI 12.5 had a massive bug that caused the screen to spontaneously dim when unlocked. In MIUI 14, some users complained of the brightness slider sticking.
How to update firmware:
- Go to Settings. → Updating the system.
- Slip the button to check for updates.
- If a new version is available, download and install it.
If automatic updates do not help:
- 🔧 Install firmware manually through Recovery:
HyperOS
MIUI
After the update:
- 🔄 Reset the display settings (see Section 2).
- 📱 Check the brightness in different scenarios (when charging, in a dark room, on the street).
If the screen dims even at 50% charge, check the settings of Ultra energy saving in Settings → Battery.