Owners of Xiaomi, Redmi and Poco smartphones often experience a display that suddenly drops in brightness for no apparent reason, a phenomenon that can occur at any time, whether while playing, watching a video or even just reading the news. The annoying effect of fading an image greatly affects the comfort of using the device, especially in bright sunlight or in the dark.
The main reason lies in the complex system of automatic adjustment of backlights, which does not always correctly interpret the external conditions. Sometimes the problem lies in the software bugs of the MIUI shell or HyperOS, and in other cases, the fault is the hardware limitation, designed to protect the components of the smartphone from overheating.
In this article, we will discuss in detail all possible factors affecting the brightness of the display, you will learn how to distinguish a software failure from a physical malfunction, and you will receive step-by-step instructions for restoring normal backlight levels.
Impact of light sensor and calibration
The main culprit behind spontaneous brightness changes is the ambient light sensor, which is a small sensor, usually located next to the front camera or at the top of the screen, continuously reads the level of light in the environment. If the sensor gets a shadow from a finger, the edge of a case or just dirt, the system mistakenly believes that you are in the dark, and instantly reduces the brightness.
But the problem isn't always physical locking. There's an adaptive brightness feature in the MIUI shell that learns from what you do. If you manually lower the slider often at a certain level of light, the smartphone remembers that and in the future it will do the same automatically. Sometimes this algorithm fails and starts to "reset" too aggressively.
To correct the situation, try calibrating the sensor through the engineering menu, which will reset the accumulated errors and force the system to read the reference values again.
How to enter the engineering menu for calibration
Dial the code ##6484# in the call app. In the menu that opens, select Light Sensor or Light Sensor. Press Calibrate and follow the on-screen instructions to close and open the top of the smartphone.> It is worth noting that on some models, such as the Redmi Note series or Xiaomi Mi, the sensor can be software-covered under the screen. In such cases, even a transparent black-framed film can cause incorrect work, causing the screen to constantly flicker or darken, closing and opening the top of the smartphone. To prevent damage to internal components and the battery, the system forcibly reduces the clock speed and brightness of the display. The smartphone screen is one of the most energy-intensive elements and a powerful source of heat. By reducing its brightness, the Android operating system tries to quickly cool the device. This is a standard behavior laid down by engineers and bypass it with software methods is difficult without risking the hardware. However, there is a nuance associated with background processes. If you have many applications that consume resources in the background, the processor warms up more than necessary. Check whether you run a “heavy” software program, which is not running from the inside, but you use it in the heat, but you are not using it in the street, but you are not using it in the heat. In such conditions, screen dimming can be almost instantaneous and very strong, making the image barely visible. The autobrightness settings in MIUI and HyperOS Shells from Xiaomi have their own backlight control algorithms that can conflict with standard Android settings. The latest versions of HyperOS and MIUI 14 add additional levels of detail to control the screen, which the user may not notice. First of all, it is worth checking whether the function “Autobrightness” is included in the notification curtain. Sometimes after a system update, this option can activate itself. Also in the section on the screen, there is more aggressive mode, or the “Aption” is more aggressively noted. These features, designed to reduce eye strain, often add a yellow filter and reduce the overall brightness of the matrix. If you accidentally activate them on a schedule, the screen will appear darker than usual even at the maximum position of the slider. To access the advanced settings, go along the path: Settings → Screen and brightness. Here you can find additional switches such as “DC-dimming” (on OLED screens), which also affects the perception of brightness at low values. The effect of energy saving mode is a powerful tool that radically changes the behavior of the smartphone to extend battery life. When the battery charge is lowered, the system automatically reduces the level of a certain level of 20% of the screen, and the background is lowered. Unlike normal autobrightness, in energy saving mode, the brightness slider may become unavailable for change, or the maximum value will be artificially limited by software. This is done so that the user can not accidentally set the brightness to maximum and quickly discharge the phone. There is also an "ultra mode" or "super-energy saving" that turns the smartphone into a simple "caller." In this state, the interface becomes black and white, and the brightness is fixed at a very low level. Exiting from this mode returns all settings, but sometimes you need to reboot. If you notice that the screen is too high a charge, it is certain that the battery is set in advance, or that the battery is set to charge you are too high. Problems with protective glass and accessories Don't discount physical factors. Cheap protective glasses with a thick layer of glue or the wrong thickness can distort the readings of the light sensor. This is especially true for models with a cut-out drop or hole in the screen, where the sensor is located very close to the edge. Cases with high sides can also block the access of light to the sensor. If you carry a smartphone in your pocket or hold it with a certain grip that covers the upper edge, the screen will constantly blink, transitioning from the screen to the brightly changing of the screen from the upper one to the dust spot. This happens if the wizard used poor-quality glass or damaged the sensor plume during assembly. In this situation, only a repeated call to specialists will help. Software and driver failures Software errors are a common cause of unstable display. In such cases, an error in the screen driver or system process conflicts can lead to the fact that commands to change the brightness are sent incorrectly, this often happens after updating the firmware "over the air." If the problem appears immediately after the MIUI update, there is a bug. In such cases, waiting for a patch from the developers or vice versa, it helps, from the previous version, which the Fboot is controlled by the presence of the application mode. Various "vision savers," launchers, or reading apps can intercept the light sensor and dictate their brightness conditions. For diagnostics, try running your smartphone in safe mode. In this state, only system applications load. If the screen is stable in safe mode, then one of the applications you installed is to blame. ═══ ERP ═══ For quick diagnosis of the problem, you can use the following table, which will help classify the symptoms and determine the most likely cause of malfunction of your Xiaomi device. Symptoms Screen solution method darkens only in games CPU overheating (trottling) Reduce graphics, remove case, cool device Brightness jumps indoors Dirty sensor or bug Wipe screen, recalibrate sensor Maximum brightness became low Power saving mode Disables charge in the settings Screen fades in the pocket Approximation Sensor Check the operation of the sensor in the engineering menu It is important to distinguish between software dimming and physical degradation of the matrix. If the screen is dimmed screen wiped screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen screen forever, even if the a confod light is exposed to the maximum, the situation, the congear can be affected by the light, especially if the congear, the maximum possible after the transmission, or the transmission can be affected by the device. If simple methods have failed, more radical measures will be needed. Complete resetting of settings to factory (Wipe Data) eliminates software conflicts, but requires backup of data. This often helps if the problem is caused by accumulated system debris. Another method is to flash the device, and installing a global firmware version instead of Chinese (or vice versa) can solve the problem if it is caused by a bug in a particular software region. However, this requires unlocking the bootloader and having a PC. ⚠️ Warning: Self-flashing and unlocking the bootloader can lead to loss of warranty and the risk of turning the smartphone into a “brick” in violation of the process technology. In extreme cases, if nothing helps, and the problem is clearly hardware (for example, the screen does not accelerate above 50% even on a new firmware), only the replacement of the display module remains. The original Xiaomi matrixes have calibration data, so after replacing it, it may be necessary to recalibrate through the engineering menu. Remember that the use of non-original spare parts during repairs often leads to a repetition of the problem. Cheap copies of the screens may not have the correct brightness control controller, which will limit the range of adjustment. Frequently asked questions (FAQ) Why does the Xiaomi screen darken with the sunshine, and the sensor is the sunshine, and the temperature is the signal is reduced. Can you turn off autobrightness forever? Yes, you can do it in the notification curtain or in the screen and brightness settings. However, without autobrightness, you'll have to adjust the backlight manually with every lighting change, which can be inconvenient. Does the protective glass affect the sensor? Yes, it affects. If the glass has a black bezel that comes into the sensor area, or if it's too thick/turbid, the sensor will get distorted lighting data. What to do if the brightness drops after the MIUI update? Try resetting the screen, clearing the system cache, or calibrating the sensor, if the mass-out is worth waiting.