The situation when the smartphone screen does not go out during a phone conversation is one of the most annoying for owners of Xiaomi Poco X3 Pro. Instead of going out and locking when holding the device to the ear, the display continues to burn, which often leads to accidental cheek presses, turning off the microphone or completing the call. It is not just a small bug, but a serious ergonomic violation that makes using the gadget for its intended purpose almost impossible.
The reason is that the Proximity Sensor is not working properly, and this small module, located at the top of the body, is supposed to detect the proximity of a foreign object and signal to the system to turn off the display. In the Poco X3 Pro, this problem is met with an alarming frequency due to the design and factory calibration.
There are many factors, from software failures of the MIUI operating system to physical contamination of the sensor or even detachment of the plume. In this article, we will take a look at all possible causes and offer step-by-step instructions for diagnosing and troubleshooting the malfunction so that your phone will work like a clock again.
Principle of operation and location of the proximity sensor
To effectively combat this problem, you need to understand how the lock mechanism works. Modern smartphones, including the Xiaomi Poco X3 Pro, use an infrared sensor that emits an invisible beam and reads its reflection. If the beam is reflected from an object (your ear) at a distance of less than a few centimeters, the screen goes out.
The design feature of the Poco X3 Pro is that the proximity sensor is hidden under the display or is located in a narrow frame above it, making it sensitive to any interference.
The main reasons why the sensor stops responding are:
- 📱 Protective glass or film covering the sensor area with a thick layer of glue or not having a special cutout.
- 🧼 Accumulation of dust, fat, or dirt at the top of the screen that blocks IR radiation.
- 🛠️ Displacement of the sensor module after a fall or poor-quality repair of the display.
Technical detail
If you've recently changed your display or put on a new protection, the likelihood of a problem increases dramatically, and even a microscopic air bubble above the sensor can distort the readings, and the screen will burn constantly.
Diagnostics of the problem with built-in MIUI tools
Before you bring your phone to the service or reset your settings, you need to make an accurate diagnosis. In the shell of MIUI there is a powerful engineering menu that allows you to check the status of all sensors without installing third-party software.
To run the test, open the Phone app and dial the combination ##6484##. The CIT (Customer Information Test) menu will open before you. Find the "Proximity Sensor" or "Proximity Sensor" item in the list.
☑️ Testing the sensor in CIT
During the test, you'll see numerical values. When there's nothing in the way of the sensor, the value should be maximum (usually 5.0 or close to 5.0). When you cover the top of the screen with your hand, the value should drop sharply to 0.0. If the numbers "jump" or don't respond to your hand, the problem is confirmed.
⚠️ Attention: If in the test CIT The sensor shows a constant "0" even without obstacles, perhaps a software failure or hardware circuit. If it shows a "5" even with the screen closed, the sensor is contaminated or misaligned.
It's also worth checking if Mode in Your Pocket is enabled, which is designed to prevent accidental taps, but sometimes it doesn't work properly. It's located along the Settings path → Lock screen → Pocket Mode, and try turning it off and see if the problem has gone away.
Programmatic calibration of the proximity sensor
Often (iron) is fine, but the software calibration is lost, and the system has simply forgotten which values are normal and which are near-object signals, and you can get it back to normal through the same engineering menu.
Return to the CIT menu (#6484##) and select "Proximity Sensor." Press Calibrate. The system will ask you to remove your hand from the top of the phone and press OK, then close the sensor and press OK again.
The calibration process looks like this:
- Press "Start."
- Make sure the screen is clean and press “OK” (the phone will record the reference value).
- Close the top of the screen with your palm and press OK again.
- If the calibration is successful, the inscription “Pass” will appear.
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After calibration, be sure to restart the device. Without rebooting, the new settings may not apply to the current call session.
Sometimes standard calibration doesn't work, so you can try resetting the calibration data through a hidden menu, and then in the sensor engineering test, select the "Clear Calibration" option (if available in your version of MIUI) and repeat the procedure again.
Influence of protective glasses and accessories
One of the most common reasons why the screen doesn't go out is poor-quality protective glass, with Poco X3 Pro owners often complaining that the problem came just after the new protection was glued.
The thing is, the infrared beam that the sensor uses has a certain wavelength. Cheap glass can have a coating that reflects or absorbs that spectrum, or it can just be too thick in the sensor area. The adhesive base can also create an optical lens that distorts the readings.
| Type of protection | Probability of failure | Recommendation |
|---|---|---|
| The original glass of Xiaomi | Low. | Use it. |
| Black-framed glass | Tall. | Check the cutout |
| Hydrogel film | Medium | Control bubbles |
| Cheap glass 3D/5D | Very high. | Replace |
If you notice that after the glass was glued, you should try to remove the protection carefully and check the sensor, and if without the glass everything works perfectly, the reason is found, in which case you should buy a quality protective glass with the right cutout for the sensor.
Resetting and system update
If physical factors are excluded, it may be a software conflict or a bug of the current firmware version. Android operating system in conjunction with MIUI can accumulate errors in the cache of system applications responsible for phone calls.
The first step is to upgrade your system. Go to Settings → About your phone and check for updates. Xiaomi developers often release patches that fix sensors. If you have a beta version of your firmware installed, consider rolling back to a stable version.
A more radical but effective method is to reset your phone to factory settings, and it's important that you back up all your important data before you do that, because all the information will be deleted.
⚠️ Warning: Data reset will delete all your photos, contacts and apps. Make sure you remember the password from your Mi Account, otherwise the phone may be blocked after the reset.
To reset, go to Settings → About Phone → Settings Reset → Erase all data. After a clean installation without third-party software, check the sensor. If the problem is still on a clean system, the probability of hardware failure is 100%.
Hardware malfunctions and repairs
When software methods are powerless, you have to talk about hardware. The Poco X3 Pro has a design feature: the plume connecting the board to the subscreen camera and sensors can detach or oxidize.
A common cause is moisture, and even if the phone wasn't bathed in water, high humidity or steam in the bathroom could cause the proximity sensor contacts to oxidize, which may not be visible visually, but the electrical contact is disrupted.
Main hardware problems:
- 💧 Oxidation of contact sensor plume.
- 🔌 Departure of the plume connector from the motherboard.
- 🧨 Failure of the sensor module itself (requires replacement).
- 📉 Deformation of the body after falling, squeezing the plume.
To solve these problems, you need to disassemble the device, remove the back cover, turn off the battery and check the density of the plumes, often by simply soldering or replacing the plume, which is cheaper than replacing the entire display.
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If calibration and resetting fail, 90% of the time, the bottom board plume or the sensor itself at the service center need to be replaced.
Interim solutions and workarounds
While you're waiting for repairs or you can't go to the service, you can use software crutches to help minimize discomfort, and they don't eliminate the cause, but they make using the phone more convenient.
There are special applications from Google Play, such as Proximity Sensor Fix or Screen Off Pro, which use other sensors (accelerometer, gyroscope) to determine the position of the phone near the ear and force the screen to be extinguished.
You can also try to turn off Remote Control in special features settings if it is activated. Sometimes system access services interfere with the sensor. Way: Settings → Advanced settings → Special features.