How to check the proximity sensor on the Xiaomi smartphone

The problem when during a conversation the screen of the smartphone goes out on its own or, conversely, refuses to turn off when lifted to the ear, is familiar to many owners of Xiaomi, Redmi and POCO devices. In most cases, the culprit of this behavior is the proximity sensor, which ceases to correctly read the distance to the object. This is not just a minor inconvenience, but a serious obstacle to the comfortable operation of the gadget, requiring immediate intervention.

Modern Xiaomi smartphones use a variety of technologies to determine the proximity of the interlocutor, and their failures can be caused by software errors and physical damage. Before carrying the device to the service center, you need to conduct self-diagnosis to understand the true cause of the malfunction. In this article, we will discuss in detail the methods of verification, hidden engineering codes and how to calibrate the sensor.

It is important to understand that ignoring the problem can lead to accidental cheek pressing during a call, resetting a call or listening to a conversation by an interlocutor on the speakerphone. Competent diagnosis will help you save time and money, and sometimes fully restore the function without replacing parts.

The principle of operation and types of sensors in Xiaomi

To understand how to test the proximity sensor on Xiaomi, you need to know exactly how it works. In budget and mid-range models of Redmi, the most common infrared sensor located at the top of the screen next to the speaker. It emits an invisible beam and analyzes the reflected signal. If the object is close, the screen is locked. In more expensive models such as the Xiaomi Mi 11 or Xiaomi 13, often use an ultrasonic sensor built directly under the display, which allows you to abandon the cutout in the screen.

The technology gap also dictates different diagnostic approaches: Infrared sensors are extremely sensitive to contamination, wide-black-framed protective glass, and even temperature changes; Ultrazooch counterparts are less susceptible to external dirt, but can fail due to driver software conflicts or after a failed firmware update.

⚠️ Warning: Using poor-quality, wide-opaque security glasses is the most common cause of false alarms on an infrared sensor, and the frame blocks the sensor's view, and the phone "thinks" it's in your pocket.

Understanding your sensor type is critical to your solution, and if you have a model with a subscreen sensor, physical cleaning of the top of the body may not work because the problem is deeper, but for classic models, rubbing the area with a speaker often works wonders.

Using the Engineering Menu for Diagnostics

The most reliable and professional way to test the proximity sensor on Xiaomi is to log into the CIT (Customer Information Test) engineering menu, which is a hidden part of the system that allows you to test each module of the smartphone separately, including an accelerometer, a gyroscope and, of course, light and proximity sensors.

To run a diagnosis, you don't need superuser rights or a computer connection, but just open the standard Phone app and enter a special combination of characters, and once you enter the code, the menu will open automatically, without having to press the call button.

##6484##

When you go to the CIT menu, you'll see a list of all the tests you can find, which might be called the Proximity Sensor, the PSensor, or the number that matches your device (often one of the first items on the list), and you'll click on it and you'll be taken to the testing window, where you'll see the current sensor readings.

In normal conditions, when nothing interferes with the sensor, the value should be maximum (usually 5.0). When you close the sensor with your finger or palm, the value should instantly change to 0.0. If the numbers do not change or "jump" without touching, this indicates a malfunction.

Verification through system settings and applications

If for some reason, the input through the engineering code is not possible (for example, in some global versions of firmware, the code can be changed or blocked by the operator), you can use the standard system tools. MIUI The new HyperOS has built-in tools for hardware inspection.

Go to Settings → About Phone → All settings and click on the kernel or processor version several times to get into the testing menu (not all models). A more universal way is to use the MIUI Diagnostic or Service app, which is pre-installed on many devices, and you can also find a proximity sensor test.

Alternatively, third-party apps from Google Play, like the Proximity Sensor Test or Sensor Test, request sensor access and output a graph or numerical value in real time, which is a great way to double-check the data from the engineering menu.

When using third-party applications, pay attention to the graph, it should be sharp: either 0 or 5. Smooth transitions or hanging in intermediate values (for example, 2.0 or 3.5) indicate a software failure or degradation of the sensor.

Calibration of the sensor: software solution

Often, the sensor is physically functional but the reading is downed, and calibration will help, a procedure that trains the system to interpret the signals coming from the sensor correctly. On Xiaomi smartphones, calibration often happens automatically when it is first turned on, but may require manual intervention after changing the screen or glass.

You can use the same CIT engineering mode for manual calibration. Once you enter the Proximity Sensor test, close the sensor with your finger, press the calibration button (usually at the bottom of the screen), then remove your finger and press the button again. The system will record the minimum and maximum values.

There is also a deeper method through the Android engineering menu, which can be accessed through the Engineer Mode app (APK installation required). In the Hardware Testing → PSensor section, you can find the PSensor Calibration button.

⚠️ Warning: Do not calibrate if you have a wide-framed protective glass on the screen, remove it first or make sure it does not overlap the sensor, or you will calibrate the phone to work with an error.

After successful calibration, be sure to restart the device, which is necessary to ensure that the new parameters are stored in non-volatile memory and applied to all system processes, including the Phone application.

Table of codes and symptoms of malfunction

For quick navigation and understanding, a pivot table can help you compare the symptoms you see with possible causes and methods of addressing them.

This table covers the most common scenarios, but if none of the methods work, the problem may lie in the hardware, such as the plume or the sensor module itself.

Physical causes and cleaning of the device

Don't discount the banal dust and fat, the proximity sensor hole is very small and over time gets clogged with earwax, pocket dust or cosmetics, and this creates an opaque film that the infrared beam can't pass through.

To clean, use a soft microfiber slightly moistened with isopropyl alcohol. Don't use aggressive chemistry or water. Gently wipe the area above the screen where the speaker is located. You can use a dry toothbrush with soft bristles to clean the dust from the speaker's mesh, which can also interfere with the sensor.

💡

If you have an iPhone with FaceID or a Xiaomi with a subscreen sensor, mechanical cleaning from the outside may not help. In such cases, it often requires disassembling and cleaning the sensor from the inside, as contamination can be between the display and the frame of the case.

Also check if the protective glass has unstuck at the edges. Even a microscopic gap can create glare or shadows that the sensor perceives as an obstacle, and temporarily removing the protective coating is the best way to eliminate this factor.

Hardware breakdowns and replacement of components

If software methods, calibration and cleaning failed, there is likely a hardware breakdown, which could be a failure of the sensor itself, a plume break (especially if the phone fell), or a problem with the power controller on the motherboard.

In models with a separate sensor module (located on a button plume or on a separate board under the screen), replacement is inexpensive. In modern devices where the sensor is integrated into the screen or glued to it, replacing may require repainting of the display, which is much more expensive.

Diagnostics in the service center with an oscilloscope will allow you to accurately tell whether the signal from the sensor is coming to the board. If there is a signal, but the screen does not respond, the problem is in the software. If there is no signal, you need to replace the hardware component.

Do not attempt to disassemble the phone yourself if you have no experience, especially if the device is warranty.Opening the case will result in a loss of warranty service.

Frequently Asked Questions (FAQ)

💡

In 80 percent of cases, the solution is to remove the wide-framed protective glass or simply clean the speaker area. Don't be in a hurry to change the screen without checking for these factors.