The situation when during a phone call the screen of Xiaomi smartphone continues to glow, rather than go out, is familiar to many users. It is not just an annoying factor that distracts from the conversation, but also a real risk of hitting the end of the call button with your cheek or activating loud communication. The approach sensor is a special sensor that must respond to the location of an object (your ear) in the immediate vicinity of the top of the device body.
Modern Redmi and Poco models often use a virtual sensor that relies on artificial intelligence algorithms, making it different from traditional physical sensors. If you find that the screen doesn't turn off, the problem can be either software failure or the mud on the surface of the glass. Understanding how this component works is the first step to solving the problem.
In this article, we will discuss how to force a function to be enabled, calibrate through the engineering menu, and what to do if the software methods do not help. You do not need to be a technician to fix this problem with your own hands, using the hidden capabilities of the MIUI or HyperOS system.
The principle of the sensor approach in smartphones Xiaomi
Traditionally, smartphones used an infrared sensor next to a speaker that emitted an invisible beam and read its reflection. If the beam was reflected (the screen is closed by the ear), the system ordered the display to be turned off. However, in the pursuit of framelessness, Xiaomi engineers began to introduce virtual sensors that analyze the data of the accelerometer and gyroscope, determining the position of the phone near the ear.
That's why, on new devices, the lack of a visible sensor window above the screen is the norm. A virtual algorithm can go wrong if the phone is lying on the surface at a strange angle or if you hold it with a non-standard grip. In such cases, the screen may not go out because the system "does not understand" that a conversation has begun.
Also, the software shell plays an important role. Android updates and security patches sometimes reset sensor sensitivity settings. A critical factor is the presence of a protective film or glass with a black frame that can block the area of operation of the physical sensor in older models, causing permanent locking or, conversely, ignoring the approximation.
It is also worth noting that some third-party calling apps may conflict with the system's screen control module. If you are using third-party software rather than a standard "bell ringer", the problem may be incorrectly requesting the status of the sensor.
Basic settings through the phone menu
The first step is to check if the screen lock function is disabled in the main call settings. This is the most common reason users encounter the problem described. Often after a system update or reset, the settings return to factory values, where some options can be deactivated.
To check, go to the Phone app and click on the three dots or gear in the corner of the screen. In the menu that opens, look for the "Incoming Calls" section. That's where the switch that controls the display's approach response hides. Make sure there's an active slider in front of the "Approach Sensor."
If the standard menu doesn't have a switch or it's active but the screen is still on, try restarting the device.
In some versions of MIUI firmware, the path to settings may differ, for example, in global versions, the option may be called "Proximity sensor", and in Chinese versions it may be called the corresponding characters. If you can't find this item, maybe your version of the shell hides it, and you need access to the engineering menu.
Calibration of the sensor through the CIT engineering menu
When standard methods fail, the CIT (Customer Integration Test) hidden engineering menu comes to the rescue, a powerful diagnostic tool built into every Xiaomi smartphone, which not only allows you to check the sensor’s performance, but also recalibrates it, resetting accumulated errors.
To enter the menu, open the Phone app and dial the combination ##6484##. If the code is entered correctly, the list of tests will open. Find the "Proximity Sensor" or "Proximation Sensor" item in the list. When you click on it, you will see the current reading: if the sensor works, the value will change from 5.0 to 0.0 (or vice versa) when you hold your hand to the top of the screen.
If the readings don't change or get stuck, look for the Calibrate button. During the calibration process, hold your finger or any object 2-3 cm away from the top edge of the screen, then remove it. The system will record new thresholds.
☑️ Checking in CIT menu
⚠️ Note: Do not change the values of other tests on the menu CIT, If you are not sure about their purpose, resetting the calibration of other sensors (for example, an accelerator) can lead to incorrect operation of the autorotation of the screen or navigation.
After a successful calibration, be sure to press "Pass" or "Success" to save the results. Then completely close the engineering menu and check the sensor's performance in real conversation, which in most cases returns sensitivity to the sensor even on older devices.
Use of calibration applications
If the built-in menu is unavailable or difficult, you can use third-party utilities from Google Play. There are specialized applications such as Proximity Sensor Reset & Calibration that automate the process of resetting sensor data. They work on the same principle as the engineering menu, but have a more friendly interface.
Once you install this app, run the test, and it'll show you a graph or a numerical value in real time, and it's diagnostic, so you can see if the sensor is responding to the hand closing, and if the graph is flat, it means that the sensor is either locked in software or has a hardware malfunction.
Some applications allow you to force the sensor to turn on if it has been disabled at the system level. However, be careful: granting excessive rights to third-party software can create a security breach.
It's important to understand that third-party applications can't fix a physical breakdown, so if the sensor is damaged, no program can make it work properly, and then you'll only have a software crutch that locks the power button when you call.
Hardware causes and the impact of accessories
Often the problem is not the software, but the physical condition of the device, and the dirt, greasy spots, or dust in the upper speaker can block the infrared sensor, and even a thin layer of dirt can scatter the beam, making the phone think it's still in the ear, or vice versa, see no obstruction.
The second common reason is cases and protective glass. Cheap black-rimmed security glass often has misaligned cutouts. If a black glass frame comes into the sensor area, the screen will constantly go out or, conversely, never go out, because the sensor is permanently closed.
It's also worth checking if the sensor plume is clamped down, and if the smartphone has recently fallen or undergone unskilled repairs, the contact may have moved away, and in such cases, a slight tap on the top of the case sometimes temporarily restores contact, but it's a signal to call the service.
| Cause of malfunction | Symptoms | Method of decision |
|---|---|---|
| Sensor contamination | The screen goes out chaotically | Wash the top with an alcohol napkin |
| Inappropriate glass | The screen doesn't go out at all. | Replace the glass with the correct cutouts |
| Failure of the | Problem after update | Calibration via CIT menu |
| Physical shock | Total sensor failure | Replacement of the module in the service center |
Make sure your device doesn't have a modified kernel or custom firmware installed that may not work properly with sensor drivers.Returning to stock firmware often eliminates software conflicts.
Alternative solutions and workarounds
If the proximity sensor is physically defective and replacement is impossible, there are workarounds, such as using the "Block in your pocket" feature if it's available in your version of MIUI, which uses other sensors to detect where the phone is in a confined space.
Another option is to use the default headset or hands-free mode, which eliminates the need to bring the phone to the face completely, making the proximity sensor irrelevant for everyday use, and some users specifically set up automatic speakerphone translation for all calls.
You can also try to turn off battery optimization for the Phone app, and sometimes the system aggressively saves energy by turning off the sensor survey in the background, which causes the screen to delay when it reaches the ear.
⚠️ Attention: Disabling battery optimization can lead to increased power consumption. Use this method only if other methods have not helped.
In extreme cases, if the screen interferes with the pressing of the cheek, you can use applications that block the screen area during the call, creating a virtual lock from random touches, even if the display itself continues to glow.