How to check the operation of the proximity sensor on Xiaomi: full instructions

Modern Xiaomi, Redmi and POCO smartphones have many sensors that make it comfortable to use. One of the most subtle but critical components is the proximity sensor, which is responsible for turning off the screen when you hold your phone to your ear, preventing accidental tapping of your cheek or ear. When this module starts to work incorrectly, the user faces serious problems: the interlocutor does not hear you while you speak, or, conversely, during a call, the speaker is constantly turned on or the reset buttons are accidentally pressed.

Many MIUI device owners mistakenly believe that the malfunction is due to a software failure or a system “glitch.” However, in most cases, the problem lies in the physical locking of the sensor, contamination or the need for software calibration. 80% of the cases of sensor malfunction is due to a protective film or case that covers the top of the display. Understanding how to check the proximity sensor on Xiaomi will allow you to quickly diagnose the problem without going to the service center.

In this article, we will take a look at all the diagnostic methods available, from simple visual tests to the use of hidden engineering menus, how to distinguish a software bug from a physical malfunction, and what steps you need to take to restore the correct operation of your smartphone. If the screen goes out on its own or, conversely, burns during a conversation, this instruction will be your main tool for solving the problem.

Symptoms of malfunction and primary diagnosis

Before you go to complex tests through the engineering menu, you need to clearly identify the symptoms. Often users confuse the failure of the touchscreen with a failure of the distance sensor. The main symptom is a situation when during a voice call the screen does not go out when you bring the phone to your face, which leads to the fact that the cheek presses the control buttons of the call, puts it on hold or puts it into speaker mode.

The reverse is also a problem: the screen may go out immediately after dialing, before you even hold the device to your ear, in which you can't press the add contact button or turn on the speaker because the display is black, and sometimes the problem manifests itself as a "shimmer" of the screen during a conversation, when the sensor is constantly turned on and off due to an unstable signal.

For the initial check, you can use the standard caller interface. Try to test the call to the time service number or voice assistant. Hold your finger to the top of the screen (usually the area above the display or the thin strip at the top) and see if the screen is responding. If the reaction is not, or it is delayed, a deeper diagnosis is required.

⚠️ Note: If the screen only goes out in certain apps (like YouTube) but works normally when calling, the problem is most likely not the proximity sensor, but the “Mode in your pocket” or accelerometer function.

Checking through the CIT (CIT Test) Engineering Menu

The most reliable way to check the operation of hardware modules on Xiaomi smartphones is to use the built-in engineering menu. CIT (Customer Integration Test: This tool is for factory diagnostics and allows you to test each sensor separately, bypassing the standard interface of the operating system, and is accessible through a dedicated debugging menu or by using the device. USSD-code.

To enter the testing mode, open the Phone app (caller) and dial the combination ##6484##. If the code did not work, go to Settings → About Phone → MIUI version and quickly click 7-10 times on the MIUI version until you become a developer. Then select CIT version from the “Additional” menu (three dots in the corner).

Once you log in, you'll see a list of all the components of the device. Find the Proximity Sensor and click on it. You'll see a numerical test window. Normally, when nothing is closing the top of the phone, the value should be close to 5.0 or display Far. When you close the sensor with your palm, the value should change to 0.0 or Near.

It's important to pay attention to the reaction rate. If the values change with a delay in the 1-2 This can indicate sensor wear or software conflict, and there is often a Calibrate button on this menu, which you can press if the reading seems to be unsettled.0Once calibrated, the phone can reboot.

Diagnostics through secret code and Mi Test application

An alternative way to test is to use the Mi Test app, which is sometimes pre-installed on devices or available for download, but the fastest method is to run the test directly through the code. Unlike the full CIT menu, this method immediately triggers a specific sensor test, which saves time.

Dial the code ##64663## or ##663## (combinations may vary depending on the version of MIUI and region). If the code is correct, a black screen will start with the words "Proximity Sensor Test." The verification principle is similar: cover the top of the smartphone with your hand. The screen should light up green or emit an audible signal when the sensor is closed and return to its original state when opened.

If the test shows that the sensor is permanently closed (near even when the hand is removed), it often indicates a software driver failure or severe contamination. Try to quickly close and open the sensor several times. If the reaction schedule is smooth but shifted, calibration will help. If the graph jumps randomly, there may be physical damage to the plume.

Calibration of the sensor: step-by-step instructions

Calibration is the process of resetting sensor sensitivity reference values, which is necessary if the sensor “sees” an obstacle where there is none, or does not respond to nearby objects. On Xiaomi devices, this procedure is often built into the same CIT engineering menu as mentioned above, but may require action.

In the approximation sensor test menu, find the Calibration button. Press it and follow the instructions on the screen. Usually, the system will ask you to remove your hand from the phone and then close the sensor. In some versions of the firmware, calibration is automatically in the background after pressing the button, taking a few seconds.

There is also a method of calibrating through the hidden menu of Android engineering settings. To do this, enter ##3646633## in the dial menu (the code may not work on new versions of Android 11/12/13 due to security restrictions). If the menu opens, go to the Hardware Testing tab → Sensor → Proximity Sensor. Here you can see the Get One Data button for taking readings and Do Calibration to start the process.

After successful calibration, be sure to restart the device, which will allow the system to apply new sensitivity factors, and if the problem persists after the reboot, a more radical intervention may be needed, such as resetting the settings or replacing the part.

Physical causes of failures: films, covers and pollution

Don't underestimate the impact of external factors on the operation of the optics. The proximity sensor on Xiaomi is an infrared emitter and receiver. Any obstacle that distorts the beam leads to errors. The most common reason is an improperly pasted protective film or glass. If the transparent part of the film is shifted and overlaps the sensor, the phone will think that it is always in the ear.

Also, dense covers with high sides or irregularly shaped cutouts can cause the problem. Even a microscopic layer of fat, dirt or dust in the area of the conversational speaker is able to scatter the IR ray. Carefully wipe the top of the screen with a microfibre dipped in alcohol solution (make sure that the liquid does not get into the speaker).

In some models (such as the Xiaomi Mi Mix or some versions of the Redmi Note), the proximity sensor is ultrasonic or laser and built into the screen. In such cases, even a thick protective glass can become a critical obstacle.

⚠️ Attention: Using cheap, black-framed perimeter glasses is a common cause of problems. The frame may partially block the sensor's operation, causing periodic failures.

If you carry your phone in your pocket without a protective case, you could get a pile of dust inside the speaker, blow the top of your smartphone with compressed air, or gently clean it with a soft brush, and often after such a simple procedure, the sensor starts to work like new.

Software solutions and resetting settings

If physical reasons are ruled out and calibration doesn't work, you should look at the software part. There's a Mode in Your Pocket feature in MIUI that uses proximity sensor data to lock the screen. A failure in this feature can simulate a sensor breakdown. Try turning this option off in the Settings menu → Lock screen and check the sensor's performance.

Third-party conflicts are also possible. Apps that monitor calls, record conversations, or have access to sensors (such as pedometers) can intercept sensor control. Try to start the phone in Safe Mode. To do this, press the off button, and when the off icon appears on the screen, press and hold it with your finger for a few seconds.

In Safe Mode, only system applications are running, and if the sensor is working correctly in this mode, it means that one of the applications you installed is to blame, remove them in turn to find the culprit, and if the problem persists in Safe Mode, the likelihood of hardware failure or deep firmware failure increases.

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Useful tip: Before resetting your settings, try simply restarting your phone in Recovery mode and selecting Wipe Cache.This won't delete your data, but it can fix system errors.

The ultimate measure of software diagnostics is a complete factory reset, and remember that this action will remove all data from the device. If the sensor doesn't work properly after resetting and installing only system updates, it's almost guaranteed to indicate that the part needs to be replaced.

Frequent Questions and Answers (FAQ)