Why the phone screen goes off when you call on Xiaomi Redmi Note 8: a complete guide to elimination

The situation of suddenly turning off the phone screen when calling on the Xiaomi Redmi Note 8 is a common problem that many users face. This behavior can be both a standard feature designed to prevent accidental cheek pressing during a conversation, and a sign of a serious failure in the operation of sensors or software. Understanding the mechanism of the proximity sensor is key to diagnosing the problem.

In normal operation, the device should respond to the ear by blocking the display, but if the screen goes out immediately after dialing or does not light up when the phone is removed, this requires intervention. Often the cause lies in contamination of the sensor or incorrect calibration, but in some cases the culprit is a protective glass or software conflict. In this article, we will discuss in detail all possible causes and ways to eliminate them.

Note that the Redmi Note 8 has a front-facing sensor at the top of the display, making it sensitive to any overlaps. If you notice that the problem came suddenly after a system update or a device crash, the algorithm of actions will differ from the standard cleaning.

Main cause: malfunction of the proximity sensor

The main culprit behind the screen turning off when talking is the proximity sensor, which is a small sensor that is usually hidden under a protective glass at the top of the screen that responds to infrared radiation reflected from close-up objects. In the case of Xiaomi, the algorithms of this component can sometimes be overly sensitive or, conversely, inert.

If the sensor is contaminated with dust, fat, or a poor protective film, it can constantly "see" the object next to it, and as a result, the system thinks that the phone is already near the ear, and forcibly turns off the display light immediately after the call begins, which is the most common technical reason that requires physical intervention or software adjustment.

⚠️ Attention: Using thick protective glasses with a black frame covering the sensor area in 90% of cases leads to incorrect screen operation during calls.

Sometimes the problem is not with the sensor itself, but with its software driver, which stops transmitting data correctly to the MIUI operating system, in which case even a clean sensor will not work properly, requiring a reset or flashing, and it is important to understand the difference between a physical malfunction and a software failure.

Checking and calibrating the sensor through the engineering menu

The first step in diagnostics is to check the sensor's performance through a built-in engineering menu, which will allow you to determine whether the sensor is responding to the approach of the hand or whether it is stuck in one state, and to enter the test mode, you need to enter a special code in the Phone application.

Open the dialer and dial the combination ##6484##. Once you enter the last characters, the CIT menu will open. In the list of tests, find the Proximity Sensor or Approximation Sensor. When you click on it, you will see a screen with numerical values and a check button.

If the values change (usually from 5.0 to 0.0 or vice versa), then the sensor is physically correct, and the problem is likely software, and if the numbers do not change or show zero constantly, even when the hand is removed, it indicates hardware malfunction or severe contamination.

The same menu often has a calibration button available. Press Calibrate and follow the instructions on the screen: usually you need to close the sensor completely, then remove your hand. After successful calibration, restart the device. This action resets the reference values of the sensor sensitivity.

Software settings and MIUI functions

The MIUI Operating Shell has its own settings that may conflict with the Android’s standard behavior. In particular, Remote Control or Power Saving Options can force the screen to go out. Check the settings in Settings → Password & Security → Privacy.

If you use a third-party call (like Google instead of the standard MIUI Dialer), try changing the default app. The standard app is often better optimized to work with a particular model's hardware sensors.

Another factor may be In Your Pocket mode, which is designed to lock the screen in the dark, but on the Redmi Note 8, it sometimes works falsely. Turn off this option in call settings or in the special Service app if it is installed separately.

Effects of protective accessories and pollution

As mentioned earlier, mechanical obstructions are a common cause of failures. Dust stuffed into the mesh of a conversational speaker where the sensor often hides creates permanent shadow. Careful brushing with a soft brush or using a pear to purge can solve the problem without deep interference with the system.

Security glasses with colored edges or poor-quality adhesive layers also block infrared radiation. If the problem disappears after removing the glass, you will have to accept the lack of protection or choose a thinner option that does not cover the upper frame of the display.

⚠️ Note: Do not use alcohol or aggressive solvents to clean the sensor area, as they may damage the oleophobic screen covering or damage the sensor itself.

In some cases, users experience the effect of a screen going out because of a finger touching the top of the screen while dialing, which is not a malfunction, but a feature of capacitive screens, and the solution is one: try not to block the top of the smartphone when initiating a call.

Resetting and system update

If the software failure is system-based, you may need to reset your settings. Before you do that, make sure to back up your data. Go to Settings → About Phone → Settings Reset → Erase all the data. This will bring the software back to factory status, fix driver conflicts.

Check for system updates. Xiaomi developers periodically release patches that fix sensors. Go to Settings → About Phone → MIUI version and press the Update Check button. If a new version is available, install it.

In rare cases, a rollback to the previous firmware version helps if the problem occurred after the update, but it is a complex procedure that requires unlocking the bootloader and using the computer, and for most users, a reset will be enough.

Hardware repair and replacement of components

When software methods and cleaning fail, and in the engineering menu, the sensor shows zero values or does not respond, it is a failure. On the Redmi Note 8, the proximity sensor is often integrated into the tail of the front camera or into a separate module under the screen.

Replacing this component requires disassembling the device, and if you don't have experience, you should go to a service center. The cost of replacing the sensor is usually low, but the work of disassembling the monoblock can cost more than the component itself.