Xiaomi smartphones, including the Redmi and POCO series, often face the problem of incorrect proximity sensor operation, which is manifested in the fact that during a conversation the screen does not go out when the phone is brought to the ear, or, conversely, goes out immediately after the call begins, this behavior significantly complicates communication, since with the cheek you can accidentally press the end button or turn on the speaker, the problem can be in both software failure and physical damage to the sensor.
Before you take a device to a service center, you need to do a thorough diagnosis. There are several proven ways to determine whether the proximity sensor is working correctly. We'll look at how to use the built-in engineering menu, third-party applications and visual inspection. Understanding the cause of a malfunction will help you choose the right solution, from simple calibration to replacement of the part.
In this article, we will go into detail on each step of the validation process, how to interpret the data and what to do if the tests show a negative result, and it is important to act consistently to eliminate software errors on either MIUI or HyperOS firmware.
Symptoms of sensor malfunction
The first step in diagnostics is to observe the behavior of the device in real-world conditions. If the screen of the Xiaomi smartphone does not respond to the approach of objects to the top of the body, this is a clear sign of failure. Often users notice that the interlocutor hears himself in the speaker, although the phone is near the ear, because the screen did not go out and switched the sound to the auditory speaker.
The reverse is also a problem, because if the display goes out immediately after dialing or at the beginning of a conversation, when the phone is still in your hands, the sensor can see the obstacle where there is none, which can be caused by pollution, protective film or a malfunction of the system drivers.
⚠️ Warning: If the screen goes out chaotically even without incoming calls, such as watching a video or reading, this may indicate a serious software conflict or physical closure of the sensor contacts.
Sometimes the problem is temporary and only occurs in certain applications, such as Viber, Telegram or WhatsApp, in which case it is worth checking the permission settings for specific programs. However, if failures are observed in the standard Phone application, a deep check of the hardware is required.
Diagnostics through CIT Engineering Menu
The most reliable way to test the health of equipment on Xiaomi devices is to use the built-in CIT (Customer Integration Test) menu, which does not require the installation of additional software and provides access to testing all the modules of the smartphone.
Enter the code ##6484## or ##4636##. Once you enter the last digit, the menu should open automatically. If the codes don't work, your firmware version may restrict access to these features, and then you will have to use the ServiceInfo app from the official GetApps store.
In the list that opens, select "Proximity Sensor" or "Proximity Sensor." You'll see a test window. Here you'll see the current readings of the sensor. To check it, hold your palm to the top of the screen, close the speaker area, and then remove it.
When working properly, the numbers on the screen should change. Usually, the value of "0" means that there is no obstacle, and "1" or "5" (depending on the model) - that the sensor is closed. If the numbers do not change or change with a long delay, the problem is confirmed.
☑️ Checking in CIT menu
Use of third-party applications
If you have limited access to an engineering menu or it seems too complicated, you can use specialized applications from Google Play, which provide more visual information and often have a calibration function. One of the most popular solutions is the Proximity Sensor Reset or Phone Doctor Plus app.
Once installed, run the program and give it the permissions it needs. Most of these utilities show a graph or a numerical value in real time. When you put your hand up to the screen, you should see a sharp jump in readings. A smooth change in values can indicate that the sensor is contaminated.
Some apps allow you to do the test in the background, which is useful for detecting intermittent issues when the sensor is working now or then normally, run the test and walk around with the phone for a few minutes, periodically closing the top of the screen.
Physical causes and pollution
Often, the reason is not electronics, but simple pollution. The proximity sensor on Xiaomi smartphones is usually located in a narrow strip above the screen. Even a thin layer of fat, dust or glue residue from the protective film can block infrared radiation.
Wash the top of the screen carefully with a soft microfiber slightly soaked in alcohol solution, make sure the protective glass or film does not overlap the sensor, sometimes the factory film is glued with a bias, which leads to permanent false positives.
It's also worth checking the case. Some security accessories have too high sides that can physically interfere with the sensor or accumulate dust in the vicinity. Remove the case and repeat the check.
⚠️ Warning: Do not use harsh chemicals or abrasive materials for cleaning.This can damage the oleophobic screen covering and exacerbate the sensor sensitivity problem.
If the problem persists after cleaning, there may have been mechanical damage, and the phone's fall could have caused the sensor plume to detach from the motherboard or damaged the touch element itself.
Software calibration of the sensor
In some cases, the sensor is physically functional, but it's downed, the system thinks the distance to the object is greater or less than it really is, and there's a calibration procedure to solve this problem, and you can do it through the same CIT engineering menu.
When you're in the Proximity Sensor, look for a Calibrate or Calibrate button. Follow the instructions on the screen: you usually have to close the sensor with your hand first and then open it, and the system will record new reference values.
An alternative calibration method is available through a hidden menu of engineering settings. Enter the code ##6485##. In the list that opens, find parameters related to calibration (often these are items with codes starting on a PC or PS). However, this method requires caution, since changing the wrong parameters can disrupt the radio module.