Calibration of the light sensor on Xiaomi Redmi Note 8 Pro: fix autobrightness once and for all

Xiaomi’s light sensor is responsible for automatic screen brightness control, a feature that should save battery power and reduce eye strain. However, Redmi Note 8 Pro owners often face a problem: the screen will spontaneously dim in a bright room or, conversely, blind at dusk, the reason lies in the failure of the sensor calibration, which can occur after a MIUI update, mechanical damage or prolonged use of the device.

In this article, we will discuss three official calibration methods (including hidden engineering settings), explain how to check the performance of the sensor without special tools, and warn against common errors that can aggravate the problem. If your Redmi Note 8 Pro suddenly ceased to respond adequately to lighting, do not rush to carry it into service: in 90% of cases, the problem is solved software in 5-15 minutes.

To successfully calibrate, you don't need root rights or complex hardware, but you just have to follow the instructions and take into account the nuances associated with the MIUI version (relevant for firmware from MIUI 11 to MIUI 14).

Signs of incorrect operation of the light sensor

Before you start calibrating, make sure that the problem is really related to the light sensor.

• 🌞 The screen becomes too dim in bright ambient light (for example, outside during the day), despite the on autobrightness.
• 🌙 In a dark room, the brightness does not decrease, which causes the eyes to quickly get tired.
• 🔄 Brightness changes chaotically without changing the lighting (for example, when watching a video).
• ⚡ Autobrightness shuts down on its own after rebooting or locking the screen.
• 📱 In the screen settings there is no slider for brightness adjustment (rarely, but occurs after resetting the settings).

If you see any of these signs, the probability of software failure of the sensor is ~85%. The remaining 15% are hardware malfunctions: contamination of the sensor (dust, fat), mechanical damage (cracks on the glass in the sensor area) or plume collapse. Before calibrating, be sure to inspect the top of the screen - the light sensor on the Redmi Note 8 Pro is located to the right of the speaker (see photo below).

📌 Quick test: Close the sensor with your finger and move the phone from a dark room to a light room. If the brightness of the screen does not change, the problem is exactly in the sensor. If there is a reaction, but it is inadequate (for example, the screen becomes brighter when darkened), calibration is required.

Calibration Preparation: What to Do in Advance

Calibration of the light sensor is not a difficult procedure, but it requires preparation, and neglecting these steps can lead to inaccurate results or even make things worse.

• 🔋 Charge your phone to at least 50% – this will prevent a sudden shutdown during calibration.
• 📱 Make sure there's no protective film or glass on the screen that covers the sensor area, and even a thin layer can distort the readings.
• 🌡️ Check the temperature of the phone: if it overheats (for example, after games), let it cool for 10-15 minutes.
• 🔄 Turn off all energy saving modes in Settings → Battery, as they can block the operation of sensors.

We also recommend that you record the current screen settings (brightness, color temperature) so that after calibration, you can return them if necessary. → Display.

⚠️ Note: If you have recently updated MIUI before the new version, and the problem with autobrightness appeared immediately after that - first try to roll back the update or reset the screen settings to factory (Settings) → System system → Resetting settings → Reset the display settings. In 30% of cases, this solves the problem without calibration.

If you use custom firmware (like LineageOS or Pixel Experience), note that standard calibration methods may not work, requiring manual editing of configuration files via ADB or terminal, a method we will discuss in the last section of the article.

Method 1: Calibration through the engineering menu (the most reliable way)

The Engineering Mode is a hidden MIUI settings section that allows you to test and calibrate your smartphone hardware, including the light sensor, which works on all versions of the Redmi Note 8 Pro regardless of the firmware region.

Step-by-step:

1. Open the phone app and enter the combination: ##6484###
2. The Manual test menu will appear on the screen. Select the Light sensor.
3. At the top of the screen, you'll see the current sensor readings in lux: 🌞 In bright light: 10,000–50,000 Lx 🌄 In room lighting: 300–1000 Lx 🌙 In the dark: 0-50 Lx

Calibrate

After calibration is completed, restart the phone.

If there is no Calibrate in the engineering menu, then your version of MIUI does not support it, in which case use Method 2 (through developer settings) or Method 3 (manual calibration via ADB).

⚠️ Warning: Do not change other options in the engineering menu unless you understand their purpose! For example, incorrect settings of the Touch screen or Gyroscope can lead to the inoperability of the sensor or gyroscope.

Method 2: Calibration through the developer settings

If the engineering menu is not available or does not contain calibration options, you can use the developer mode, which is less accurate, but is suitable for most users.

Algorithm of action:

1. Activate Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times. You will be notified “You are a developer”.
2. Go back to the basic settings and open a new Developer section (usually at the end of the list).
3. Scroll down and find the Debugging by USB item – turn it on (this is a must for further action).
4. Next, look for the option of Calibration of the light sensor (in some versions of MIUI it is called Sensor calibration).
5. Follow the instructions on the screen: the system will ask you to place the phone in different lighting conditions (bright light, shadow, darkness) and confirm the readings.

After calibration, check the autobrightness:

1. Turn on autobrightness in Settings → Display → Autobrightness.
2. Move your phone from a dark room to a light room and back, and the screen reaction should be smooth, without any sudden jumps.

If the brightness is still not adjusted correctly, try resetting the sensor settings:

1. Back to Settings → For developers.
2. Find the Reset sensors (or Reset sensors) and confirm the action.
3. Reboot the phone.

💡

If the autobrightness still doesn't work well after calibration, try turning it off for 10 minutes and then turning it back on, sometimes helping to zero out the sensor's temporary errors.

Method 3: Manual calibration via ADB (for power users)

This is a good way to go if the first two methods didn’t work or you’re using custom firmware, and you’ll need a computer with Xiaomi drivers installed and an ADB (Android Debug Bridge) tool.

Instructions:

1. Download and install Google’s Platform Tools (includes ADB).
2. Connect the Redmi Note 8 Pro to your computer via USB, enable debugging via USB (see the previous section).
3. Open the command prompt (cmd in Windows or Terminal in macOS/Linux) and type: adb devices Make sure your phone appears in the list of devices.
4. Enter the command to calibrate the light sensor: adb shell am start -a android.settings.LIGHT_SENSOR_CALIBRATION On the screen of the phone will appear the calibration wizard – follow his instructions.
5. If the previous command didn’t work, try an alternative method: adb shell settings put system. screen_brightness_mode 1 adb shell settings put system screen_auto_brightness_adj 0.5 This command resets autobrightness settings to factory values.

It is also useful periodically (every 2-3 months) to perform a soft reset calibration:

1. Turn off autobrightness in the settings.
2. Manually set the brightness to 50%.
3. Turn the autobrightness back on.

This simple procedure helps to “zero out” the timing errors of the adjustment algorithm.

FAQ: Frequent questions about the light sensor on the Redmi Note 8 Pro