How to adjust the light sensor on the Xiaomi phone: full instructions with nuances

Light sensor in smartphones Xiaomi, Redmi and POCO It is responsible for automatic brightness control, a function that should save battery power and reduce eye strain, but many users are faced with the fact that autobrightness does not work correctly: The screen is too dim in sunny weather, too bright in the dark, or changes the backlight abruptly at the slightest change in lighting, most often due to incorrect sensor calibration or software failures.

In this article, we’ll break down all the ways to configure the light sensor on Xiaomi phones – from the standard tools in the Settings menu to hidden engineering modes and manual calibration. You will learn how to check the sensor, reset it to factory settings and even physically clean the sensor if the problem is pollution. 4/5) We will give some recommendations - their sensors often require a special approach.

Before you start setting up, make sure that the problem is with the sensor, not the firmware or the screen. For example, if the brightness does not change at all, maybe the auto-adjustment function is disabled or the sensor is physically damaged. → Display. → Autobrightness and turn the slider on/off. If there's no change, read the Fault Diagnostics section.

How does the light sensor in Xiaomi smartphones

A light sensor (or photosensor) is a miniature module, usually located next to a front-facing camera or speaker, that measures the intensity of ambient light and transmits the data to a processor that adjusts the brightness of the screen, and on Xiaomi phones, it is responsible for this:

• 📱 Hardware: the sensor itself (e.g, TSL2572 or APDS-9930 model POCO F3 Xiaomi 11T).
• 🤖 Software part: algorithms MIUI, Analyze sensor readings and apply correction.
• ⚙️ Custom settings: manual calibration in the Settings menu or through the engineering menu.

Ideally, the sensor should respond to light changes smoothly, without sudden jumps.

• ⚡ Too aggressive reaction (the screen flickers at the slightest movement of the hand).
• 🌑 Insufficient brightness in sunny weather (no screen is visible outside).
• ☀️ Excessive brightness in the dark (blind eyes at night).
• 🔄 Brightness getting stuck at one level (the sensor forgets to adapt).

The causes of such failures are diverse: from sensor contamination (dust, fingerprints) to software errors after the update. MIUI. In the following sections, we will discuss how to diagnose and fix each of the problems.

Customize autobrightness through the standard menu

Before you climb into the engineering menus or reset the settings, try adjusting the sensor through standard tools. MIUI. This method is suitable for all Xiaomi, Redmi and other models. POCO (including Redmi Note 10 Pro, Xiaomi 12, POCO X4 Pro and others.).

Instructions:

1. Open the Settings → Display.
2. Activate the “Autolightness” slider (if it is turned off).
3. Click on the icon. ⚙️ next to the slider (or tap on the slider itself in some versions) MIUI).
4. In the menu that opens, select “Calibration of the light sensor”.
5. Follow the instructions on the screen: The phone will suggest placing it under different light sources (e.g., in the shade, then in bright light) and confirming the current conditions.

If the option "Calibration" is missing, then your model does not support manual adjustment through the MIUI. In this case, go to the engineering menu.

Place your phone on a flat surface

Make sure the sensor is not covered with a cover or film

Turn off the energy-saving mode.

Close all applications that work in the background-->

Important nuance: after calibration, give the phone 5-10 minutes to adapt. MIUI They analyze new data and adjust the brightness to your preferences. If the problem persists after that time, then proceed to the following methods.

⚠️ Note: Do not calibrate at extremely low (less than 15%) or extremely high (over 85%) battery levels, which can cause the process to fail due to automatic power-intensive shutdowns.

Manual setting through the engineering menu (MTK/Qualcomm)

If standard calibration doesn't work, try manually adjusting through an engineering menu. This method works on phones with MediaTek processors (MTK) Qualcomm Snapdragon, but the ways to access the menu are different.

For MediaTek (Redmi models) 9A, POCO M3, Xiaomi Civi and others.):

1. Open the Phone app.
2. Enter the combination: ##36446337## (or #3644633## on some firmware).
3. Go to Hardware Testing → Light Sensor.
4. Press Calibrate and follow the instructions (usually cover the sensor with your hand, then open).

For Qualcomm (models Xiaomi 11 Lite, POCO F3, Redmi Note 11 Pro+ etc.):

1. Enter the phone: ##4636###.
2. Choose Testing → Light Sensor.
3. Write down the current values (e.g. Lux: 100 in room light).
4. If the values do not change when the lighting changes, the sensor is defective.

You can also manually set the trigger thresholds in the engineering menu, for example, if the screen is too dim outside, increase the Max Lux value (maximum illumination, which reaches 100%).

• 📝 Get in the Light Sensor. → Set Calibration.
• 🔢 Install Min Lux = 10 (for dark rooms), Max Lux = 50,000 (for sunlight).
• 🔄 Save the settings and restart the phone.

Diagnostics of sensor faults

If the setting didn't work, it could be that the sensor is physically damaged or contaminated, and you can check this in a number of ways.

Visual inspection:

• 🔍 Inspect the area around the front camera – the sensor looks like a small round or square hole (sometimes closed with transparent plastic).
• 🧴 Wash it with a soft wipe (do not use alcohol or abrasives!).
• 🚫 Make sure the sensor is not covered by a film, cover or sticker.

Verification through annexes:

Install utilities for sensor testing, such as:

• 📱 Sensor Test (shows sensor values in real time).
• 🔦 Light Meter (measuring the illumination in the suites).
• 🛠️ Phone Doctor Plus (Complex Diagnostics).

If the app shows Lux: 0 in any light, the sensor doesn't work. If the values change but the autobrightness doesn't respond, the problem is the firmware or settings. MIUI.

Test with another case:

Some cases (especially those with high sides) can overlap the sensor. Remove the case and check for autobrightness. If the problem is gone, pick up a case with a notch for the sensor.

⚠️ Note: If the sensor is physically damaged (for example, after a phone crash), it will cost 1,500-3,000 rubles to replace it at the service center. AMOLED-With screens (such as the Xiaomi 13), the sensor is often soldered into the display module, so replacing it may require a complete disassembly of the phone.

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If the sensor is working, but the autobrightness is buggy, try turning it off for 10 minutes, then turn it on again. MIUI.

Software solutions: reset, update, rollback

If the sensor is in good working order, but the autobrightness is not working properly, the problem may lie in the firmware or system settings.

Resetting the screen settings:

1. Go to Settings → Display → Additional.
2. Select Reset Brightness Settings (or Reset Default Settings).
3. Confirm the action and restart the phone.

2. Clearing the cache MIUI:

• 📱 Go to Settings. → Annexes → Application management.
• 🔍 Find “Settings” (system application) and open it.
• 🧹 Click Clear Cache and Clear Data (Warning: This Will Reset Some Personal Settings!).

3. Update or rollback of firmware:

In some versions MIUI (for example, MIUI 13.0.4 for Redmi Note 10) there were bugs with light sensor:

1. Settings → About the phone → System update.
2. If there are no updates, but the problem has appeared after the last update – consider rolling back to a stable version via Fastboot or Recovery.

On Xiaomi models with MediaTek processor (for example, Redmi 9, POCO M2) Firmware rollback can block the bootloader. Before the procedure, unlock it through the official Mi Unlock tool.

How to use your phone without autobrightness

If the light sensor is not repairable, and autobrightness is critical to you, you can emulate its work manually or using third-party applications.

Manual adjustment through the notification panel:

• 📲 Add the brightness slider to the Quick Settings panel (swipe down from the top edge of the screen) → ⚙️ → Edit).
• 🔄 When changing the lighting, adjust the brightness manually (for example, outdoors - 80%, indoors - 40%).

Applications for automatic adjustment:

Utilities like Lux Auto Brightness or Velocity can replace the standard autobrightness using:

• 📊 Specified profiles (e.g., “House”, “Street”, “Night»).
• ⏱️ Timers (automatic brightness decrease in the evening).
• 🌡️ Approximate sensor (to determine if the phone is on the table).

3. Setup through ADB (for advanced users):

If you have access to ADB, You can force the brightness values:

adb shell settings put system screen_brightness_mode 1


adb shell settings put system screen_brightness 150

Where 150 is the brightness level (0 to 255).

adb shell settings put system screen_brightness_mode 0

⚠️ Attention: Manual autobrightness apps can drain the battery faster because they are constantly running in the background. → Battery → Optimizing the battery.

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If the light sensor is completely out of order and repair is not feasible, the best solution is to turn off the autobrightness and use manual adjustment or third-party applications, which will eliminate sharp spikes in brightness and prolong the screen life.

Features of settings for popular models

Some Xiaomi phones have unique nuances in the light sensor, and we have compiled recommendations for the most common models:

Xiaomi Redmi Note 8/9/10 Pro:

• 🔧 The sensor is often contaminated by being close to the speaker.
• 📉 V MIUI 12-13 avtobrightness may freeze after the update.

POCO F3 / Xiaomi 11T:

• ☀️ Nana AMOLED-The screens are more aggressive than the screens. IPS. Reduce sensitivity in the engineering menu (Max Lux) = 30000).
• 🔄 After updating to MIUI 14 may require recalibration.

Xiaomi Mi A2/A3 (Android One):

• 🤖 These models run on pure Android, so the engineering menu opens with code ##4636##.

Redmi 7/8/9 (budgetary models):

Frequent questions about setting up the light sensor