Check and configure the proximity sensor on Xiaomi Poco X3 NFC

The proximity sensor problem on the Xiaomi Poco X3 NFC is one of the most frequent requests to the support team of the owners of this popular smartphone. Users complain that during a conversation the screen goes off on its own or, conversely, does not turn off when you bring the phone to your ear, which causes calls to be dropped with your cheek or loud communication is turned on. This is not just an annoying bug, but a functional failure that can be caused by a software error and physical damage.

Before you take the device to the service center, you need to conduct a self-diagnosis. The MIUI operating system, on which the shell of the smartphone is based, provides hidden engineering menus and special tests to determine exactly whether the sensor is working correctly. Often the problem is solved by simple calibration or cleaning the upper part of the case from contamination, so do not rush to conclusions about the breakdown.

In this article, we will take a look at all the available methods for checking the proximity sensor, from built-in tests to using third-party applications. You will learn how to properly calibrate the sensor, what to do if the screen turns black ahead of time, and what environmental factors can affect its operation. Competent diagnosis will help save time and money, returning the device to comfortable use.

CIT Engineering Menu: The Basic Diagnostic Method

The most reliable and accurate way to test the health of all Poco X3 NFC hardware modules is to use the built-in CIT (Customer Integration Test) engineering menu, a tool designed specifically for factory tests that isolates the proximity sensor from the shell software add-ons by showing its raw data.

To enter the menu, you need to open the standard Phone app and dial the special code ##6484##. Once you enter the last star, the menu will open automatically. SIM-The card is active, or try the combination ##4636##, although the first option is preferred for testing iron.

In the list that opens, select Proximity sensor. You will see a test window that displays the current sensor readings. In a normal state, when nothing is covering the top of the screen, the value should be 5.0 (or close to 5.0). If you hold your palm to the top of the smartphone, the value should change to 0.0.

⚠️ Warning: If the value floats on its own or does not respond to hand closing of the top of the screen, this indicates a hardware malfunction or a serious driver failure.

The CIT testing process cuts out software bugs, and if the sensor works perfectly on this menu (the numbers clearly change from 5.0 to 0.0 and back), then the problem lies in the MIUI settings or third-party applications, and if there is no reaction or the readings are incorrect, deeper intervention is required.

Checking through the hidden menu of engineering tests

An alternative to direct code entry is to log in via the settings menu, which may be more convenient if the dial keyboard blocks the entry of special characters. This method also leads to diagnosis, but through the Android system interface.

You need to go to Settings → About phone and quickly click on MIUI version several times (about 7-10 times) until you see the words "You became a developer". After that, a new section "Additional" or "Extended settings" will appear in the main settings menu, where you need to find the item Engineering menu or CIT.

Inside this menu, the interface may vary depending on the firmware version, but the way it works is the same. Find the Proximity Sensor test. It's important to pay attention to the response rate. When you put your hand up abruptly, the screen should change color or reading instantly. A delay of more than 0.5 seconds may indicate sensor degradation or plume problems.

• 🔍 Check the purity of the glass: even a thin film of fat can distort readings.
• 📱 Make sure the protective glass does not cover the sensor at the top.
• 🌡️ Avoid overheating: with strong heat, sensors can work unstablely.

If the engineering menu is successful, but there are problems in life, it is worth checking the settings of calls. Sometimes third-party applications for calls (for example, Google Phone or Truecaller) conflict with the system control of the sensor.

Using third-party applications for testing

If Xiaomi’s built-in tools are not available for some reason or you want to get more detailed statistics, you can use Google Play apps that allow you to visualize the sensor in real time and even record logs of changes.

One of the most popular and proven tools is the Proximity Sensor Reset/Fix or Sensor Test. Once installed, run the program and put the phone on a flat surface. The app will show a graph or a numerical value. A sharp change in the schedule when you put your hand will confirm the hardware part is working.

The advantage of third-party utilities is that they can force the sensor driver to reset without rebooting the entire smartphone.This is useful if you notice that after a long conversation or using navigation, the sensor stopped responding correctly.

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Before installing third-party testers, be sure to give them permission to access the sensors, otherwise they will show an error or zero values.

And you should also look at applications that show you a list of all the sensors available, like AIDA64. In the Sensors section, look for the Proximity Sensor line. If there's no such string on the hardware list at all, it's a warning sign that the system doesn't see the sensor at all, and this often happens after a failed flashing or moisture hit.

Proximation sensor calibration process

Calibration is the process of learning a smartphone to define the limits of the sensor's normal range, so if the screen goes out when the phone is on the table, or if it doesn't go out in the ear, you've lost your sensitivity threshold. On the Poco X3 NFC, you can do this through an engineering menu.

Return to the CIT menu (code ##6484##) and select Proximity sensor. In some versions of the firmware, there is a Calibration or Pass button at the bottom of the screen. If there is no button, try to close the sensor with your hand, wait for the value of 0.0, then remove your hand and press the confirmation button (if it is active). In newer versions of MIUI, calibration often occurs automatically when you press the Pass button after a successful test.

If standard calibration doesn't work, you can try resetting the sensor through the ADB (Android Debug Bridge) by connecting the phone to a computer, which requires developer rights and basic command line knowledge.

adb shell settings put system proximity_sensor_calibrated false

Once this command is completed, the device must be fully restarted, and when it is turned on, the system will recalibrate the sensor in the first place, which is safe and does not delete personal data, but can correct a software glitch where old calibration data conflicts with the current state of the sensor.

Table of typical values and states

For ease of diagnosis, it is recommended to check the readings of your device with reference values. Below is a table describing the normal behavior of the sensor in various situations.

If your scores match the last two rows of the table, then the problem needs to be solved. A constant value of 0.0 most often indicates that the sensor is stuck in a closed state due to dirt or software failure. No change in any impact is a sign of a plume break or the module itself fails.

Typical causes of failures and their elimination

Understanding the cause of a malfunction is half the success of fixing it. Poco X3 NFC owners are most likely to face three main problems: pollution, software conflict, and physical damage.

Pollution is the most common, but common, cause: At the top of the smartphone is a small hole or hidden area under the glass, where the IR sensor is located. Getting dust, pile from your pocket or greasy traces from a conversation blocks the radiation. Regularly wiping this area with an alcohol napkin solves 50% of all problems.

Software conflicts arise after MIUI updates or memory "optimizers" are installed. In this case, it helps to clear the cache or reset network settings. Physical damage, such as impacts or water, requires a module to be replaced. In the Poco X3 NFC, the sensor is often integrated into the charging port plume or into the display assembly, which makes repairs more difficult.

⚠️ Warning: If the phone falls or gets wet, disassembling yourself can lead to permanent breakage.

Another specific reason for this model is that the mesh is peeled off by the speaker inside the housing, and sometimes it shifts and overlaps the sensor, even if the glass is clean on the outside, and this is treated only by disassembling and pasting the mesh.

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In 80% of cases, the problem is solved by thoroughly cleaning the top of the screen and gluing the protective glass, which can overlap the sensor.

Frequently Asked Questions (FAQ)