Not blocked screen when talking on Xiaomi Note 8 Pro: causes and elimination

The situation when the display continues to burn while talking on the Xiaomi Redmi Note 8 Pro smartphone is one of the most common and annoying problems. Users often face the fact that the device does not respond to the ear lift, which causes the buttons to turn off the microphone, hands-free communication or end the call to accidentally be pressed with the cheek or shoulder.

The root of the problem is often the incorrect operation of the proximity sensor, which is located at the top of the body. Unlike many competitors, the Redmi Note 8 Pro model uses software emulation of this sensor, rather than a physical separate module, which makes its work dependent on calibration and absence of interference. A failure in the MIUI software, contamination of the upper frame or a pasted protective glass with an incorrect notch can be a trigger for the system to block the screen.

In this article, we will discuss in detail the mechanics of your device’s sensor system, software and hardware diagnostics methods, how to independently calibrate accurately through the engineering menu and why standard settings may not work. Understanding the principles of the accelerometer and light sensor will help you fix the malfunction without going to the service center.

The principle of the proximity sensor in the Redmi Note 8 Pro

To effectively troubleshoot, you need to understand how your Redmi Note 8 Pro detects an object near the screen. In this model, the manufacturer has abandoned the classic infrared sensor, placed in a separate hole, in favor of technology using an accelerometer and software algorithms.

This design has its advantages, such as the absence of an extra hole in the body and the ability to create a design with minimal frames. However, the software sensor is more sensitive to third-party factors. Any physical impact on the body, vibration or even a sharp movement of the hand can be interpreted by the system as a signal of approach, or vice versa, ignored when the phone is actually held to the ear.

It's important to note that the sensor is closely related to the MIUI shell. The operating system is constantly questioning sensors at a certain frequency. If the processor is loaded with background tasks or there is a failure in the drivers, the command to turn off the screen may be missed, which is why the problem often manifests itself intermittently (periodically), then appearing and disappearing.

In addition, the role of the protective film should be considered: if it closes the area of the upper speaker or has too thick adhesive layer in the area of the intended location of the sensors, this can create optical interference or change the sensitivity of the touch screen, which indirectly affects the logic of the screen lock.

The main reasons for resetting the screen lock

There are several key factors that cause the Xiaomi Note 8 Pro to stop turning off its screen. The first and most common cause is contamination of the top of the front panel. Dust, skin fat, or moisture droplets can block access to the sensory areas that are involved in determining the proximity of an object. Even a microscopic film of dirt can distort sensor readings.

The second common cause is a misplaced protective glass or film, and many accessories, especially those that are versatile or low-quality, don't have special sensor cutouts or have thickening in that location, which creates a physical barrier that the system perceives as a permanent object, which can either keep the screen going out or go out as soon as the bell starts.

The third group of reasons is due to software errors: after updating the MIUI operating system or installing application updates, Google can fly calibration settings, and third-party applications that access the phone, such as voice recorders, call recordings or smart assistants, can cause conflict, and they can intercept the control of sensors, blocking the standard algorithm of operation.

Finally, you can't rule out hardware problems that have arisen after the device crashes, because even if the screen is intact, the plume may have moved inside or the component responsible for transmitting the position of the phone may have shifted, and in such cases, the software methods may be powerless and hardware intervention will be required.

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Use microfiber and a special screen cleaner. Do not use alcohol or aggressive chemicals, as they can damage the oleophobic coating and aggravate the sensitivity problem.

Checking the performance of sensors

Before you start to do complex manipulations, you need to do a diagnostics. The MIUI shell has a powerful engineering tool built in to test all the components of a smartphone. It's the most reliable way to know if the system sees your finger when you move to the top of the case. It uses a special code that is typed into the Phone app to trigger the diagnosis.

You need to open the dial and enter the combination ##6484##. Once you enter the last characters, the CIT menu will open. In the test list, find the "Proximity sensor." Click on it to go into the check mode.

In the window that opens, you'll see two values: Distance and Status. If you're not holding anything in front of the screen, Distance should be high (usually 5.0), and Status should be Far (far). When you hold your palm to the top of the screen (about 2 cm), the value should change to 0.0, and the status should switch to Near (close).

If the values don't change or change randomly, the problem is confirmed, and if the calibration can help, if the test is perfect, but the screen doesn't go out in real calls, then the reason is the application conflict or the settings of the phone book itself.

Instructions for calibration of the proximity sensor

Calibration is the process of "training" a system to correctly identify a zero point. For the Redmi Note 8 Pro, this is often a crucial step. There are two main ways: through the engineering menu (CIT) and through the hidden calibration menu, starting with the deeper method available through the CIT menu, which we've already opened earlier.

When you're in the Proximity sensor test on the CIT menu, you'll notice the buttons at the bottom of the screen. There's a Calibration button. Press it. The system will ask you to remove your hand from the screen and press OK, then close the sensor and press OK again. Follow the instructions on the screen carefully. Once you've finished, the phone may reboot or just go back to the menu.

The second method involves using a special code to reset calibration data. Enter ##64663## in the dialer (if it is active on your firmware version) or try to find "Calibration" in the main settings through search. Sometimes a simple reset of the Phone application helps. To do this, go to Settings → Apps → All Apps → Phone, select "Memory" and click "Clean" (without deletting contacts, only cache and settings).

After calibration, be sure to restart the device. The first call after reboot may not be correct, as the system needs time to stabilize the sensor readings. Make 2-3 test calls, checking the screen response.

Software settings and application conflicts

If the hardware and calibration are fine, you should pay attention to the software settings. Some versions of MIUI have features that may interfere with normal operation. For example, the gesture control function or certain design themes can change the behavior of the status bar and sensor area.

It’s also worth checking if you have apps installed to record third-party calls. They often require constant access to the microphone and proximity sensor, which creates conflict with the system phone application. Try temporarily uninstalling such programs or disabling their permissions in the Settings menu → Apps → Permissions → Other permissions.

Another important aspect is the In-Pack mode, which is designed to prevent accidental taps, but if the sensor is faulty, it may not work properly. Try turning it off in the lock settings or in the phone app settings to rule out its impact on the problem.

Remember that the firmware version itself may contain bugs. If the problem has occurred after the update, check the forums for complaints from other users of the Xiaomi Note 8 Pro. Sometimes waiting for the next security patch is the only solution, but the temporary fix can be a rollback to the previous version or a reset to factory settings.

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Third-party themes and launchers often take over sensor control. When diagnosing, always switch to the standard theme and system launcher.

Influence of accessories and protective glasses

One of the most common reasons why the screen on the Xiaomi Redmi Note 8 Pro is not locked is the wrong security glass. Because the sensor in this model is software-based and tied to the top of the display, any thickening in this area is critical.

If you notice that the problem started right after you glued the new glass, remove it and check the sensor. If everything works perfectly without the glass, then the accessory physically interferes with the sensor, in which case you can try to neatly cut the hole above the speaker with a scalpel or buy a special glass labeled "Compatible with Redmi Note 8 Pro", which takes this feature into account.

Some tight bookcases or magnetic-clasp cases can create a magnetic field or physically push on the edge of the case, which knocks off the accelerometer readings. Take off the case and check the phone's naked.

Radical methods and resetting settings

If none of the above methods worked, there may have been some critical configuration errors in the system, in which case you can try resetting all settings, which will bring the phone back to factory status, so be sure to make a full backup of all important data before starting the procedure.

Resets are done through Settings → Phone → Settings Reset → Erase all data. This process will delete all apps, photos, contacts and settings, returning the software to the “out of the box” state. Often this eliminates deep driver conflicts that cannot be fixed with conventional calibration.

In the rarest cases where even a complete reset doesn't work, the problem can be a physical breakdown of the plume or the display module itself. In the Redmi Note 8 Pro, the proximity sensor is integrated into the screen design, and it can only be replaced with the display. If the phone falls or falls into the water, the probability of hardware failure increases significantly.

⚠️ Warning: When using the engineering menu codes (##...) be careful. Do not change settings that you do not understand, especially in sections related to the radio module or bootloader, so as not to turn the phone into a brick".

⚠️ Warning: If you decide to remove the protective glass yourself, do it carefully.Highing the screen with a hairdryer can damage the matrix or adhesive layer if you overdo it with temperature.

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