Owners of Xiaomi, Redmi and POCO smartphones often face an annoying problem: the display spontaneously changes brightness. This can occur while reading, watching videos or even when in your pocket when the device is locked.Disclosure of the screen not only interferes with the comfortable use of the gadget, but can indicate software failures or sensor malfunctions.
In MIUI or the new HyperOS, a sophisticated algorithm that analyzes light sensor data controls the backlighting. However, aggressive optimization and sensitive sensors often cause the phone to “think” you’re in the dark and reduce the brightness to a minimum. In this article, we’ll detail how to turn off autobrightness, calibrate the sensor, and eliminate software conflicts.
Before you start taking radical measures like resetting, you should check the basic parameters of the system, often because of activated adaptive brightness or contamination of the upper body. AMOLED-Dimming can be part of protection against pixel burnout in a static image.
Turning off automatic brightness control
The easiest and most effective way to remove unpredictable dimming is to completely disable automatic adjustment. Xiaomi’s Android shell allows you to manually set the backlight level, ignoring external conditions, this is especially true if the light sensor is not working correctly or closed with a protective glass.
To do this, you need to lower the notification curtain, find the brightness slider, and click on the A or sun icon to deactivate the automatic mode, and then you can control the intensity of the matrix's glow yourself.
If the standard slider is gone or is acting strangely, check the settings in the menu:
- 📱 Go to the Settings of the main menu of the smartphone.
- 🔍 Find the Screen or Display section and brightness.
- ☀️ Turn off the Autobrightness switch (or "Adaptive Brightness»).
Once this function is turned off, the phone will stop responding to changes in external light, you will have to manually adjust the brightness when you move from a dark room to the outside, but the problem of spontaneous dimming will disappear.
Calibration of the proximity and illumination sensor
The proximity sensor, usually located at the top of the screen or in the neckline of the front camera, often becomes the culprit of the dimming. If it is contaminated or knocked off the calibration, the system can interpret its readings as finding the phone near the ear during a conversation, which leads to the screen quenching.
Xiaomi devices have a hidden engineering menu to check and configure the equipment, accessed through a special code in the Phone app, a safe procedure that allows you to reset the sensor parameters to factory values.
To start the test, perform the following steps:
- 📞 Open the phone application (calling).
- 🔢 Enter ##6484## to log into the engineering menu CIT.
- 👆 Find the Proximity Sensor in the list).
- 🔄 Press the Calibrate button and follow the instructions on the screen (usually you need to close the top of the screen with your finger and then remove it).
⚠️ Warning: If the test fails after calibration (status does not change to Pass), try to wipe the top frame of the smartphone with an alcohol wipe. Fat spots can block the IR ray of the sensor.
Some models, especially the Redmi series, use a virtual sensor that relies on algorithms, and in such cases software calibration may not be available and a firmware update is required.
Setting up timeout and “In your pocket” mode
A common cause of sudden display quenching is the Mode in the Pocket function, which is designed to save charge and prevent accidental pressing, but often works falsely if there is a pile or keys in the pocket that overlap the sensor.
To disable this feature, go to lock settings. The path may differ depending on the version of MIUI, but it is usually in the section "Screen lock" Disabling this option will allow the screen to burn even if the sensor "feels" something.
Also, pay attention to the time before going to sleep: if set too short time (for example, 15 seconds), the screen will go out as soon as you stop touching the display.
Comparison of the main parameters of energy saving:
| Parameter | Recommended value | Effects on dimming |
|---|---|---|
| Screen timeout | 1-2 minutes | Prevents rapid quenching when reading |
| Pocket mode. | Off. | Removes false locks in your bag |
| Autobrightness | The situation | The main reason for the spikes in brightness |
| Dark subject matter | Included. | Reduces the overall brightness of AMOLED matrices |
Disabling unnecessary protection features allows you to get full control over the behavior of the display, although it requires more care when wearing a phone without a case.
Effects of energy savings
Aggressive energy saving algorithms in Xiaomi smartphones can force the screen to dim even if the slider is twisted to its maximum, which occurs when the battery power drops below a certain threshold (usually 20% or 10%).
The system limits the maximum brightness and refresh rate of frames to extend the device's life, and if you notice that the screen dims at low charge, that's the point.
To check and adjust the feeding regimes:
- 🔋 Go to Settings. → Battery.
- ⚡ Choose Performance or Balanced Mode.
- 🚫 Avoid Ultra-Energy Saving if you want maximum brightness.
💡
When the original charger is connected, the power saving mode is often turned off automatically, returning the full brightness of the screen.
It is also worth checking the settings of a particular application. Some versions of the shell have a function called Background Activity Limitation, which can affect the operation of the interface in certain use cases.
Problems with protective glasses and covers
Physical obstacles are one of the most common but common causes of blackouts: Cheap black-framed protective glass or improperly pasted film can block the light sensor.
If you've recently replaced the glass or installed a new case, and the problem came after that, the accessory is almost certainly the cause. A sensor closed with an opaque material sends a signal to the system that it's completely dark.
To diagnose the problem:
- Carefully examine the top of the screen when the light is off, highlighting it with a flashlight.
- Check if the edge of the case goes to the sensor area.
- Try temporarily removing the protective glass to check the sensor.
⚠️ Attention: Some hydrogel films will eventually become cloudy or flaky in the sensor area, which also leads to incorrect autobrightness.
Owners of models with a subscreen sensor (for example, Xiaomi 13, POCO F5) should be especially careful when choosing accessories, since the sensor area is less noticeable, but more sensitive to the quality of materials.
☑️ Diagnosis of dimming
Resetting and system update
If the software settings don't help, there may be errors or conflicts in the system after the upgrade, and resetting all settings to factory values often solves sensor problems, as it returns calibration files to their original state.
Before doing this, make sure to back up your data, as all the information from the internal drive will be deleted, which is an extreme measure to resort to if other methods have not worked.
Procedure for discharge:
- 💾 Backup your contacts and photos to the Mi Cloud cloud or your computer.
- ⚙️ Go to Settings. → The phone.
- 🗑️ Press Reset Settings. → Erase all data.
Alternative discharge method
Also, be sure to check for system updates. Xiaomi engineers regularly release patches that correct the display and sensor errors in specific models.
Hardware Display Failures
In rare cases, a blackout of the screen indicates a physical breakdown, which can be a degradation of the LED backlight (in LCD screens) or a malfunction of the display plume. If the screen dims unevenly, spots or stripes appear, this is a hardware problem.
Also worth noting is the heating of the case, which is that when the processor overheats, the system can force the screen to turn down (trottling) to reduce heat, a protective mechanism that you can't programmatically turn off.
Signs of hardware breakdown:
- 📉 Brightness drops to a minimum and does not recover after rebooting.
- 🌑 The screen goes out completely, but the phone keeps working (sound is there).
- 🔥 The device is strongly heated in the upper part before dimming.
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If resetting the settings and calibrating the sensors did not help, and the screen continues to go out - it is likely that a replacement of the plume or display module in the service center is required.
In such cases, self-repair can be dangerous, especially if the smartphone is under warranty.