Owners of Xiaomi, Redmi and Poco smartphones often face an annoying problem: during a conversation, the screen does not go out when the phone is held to the ear, or, conversely, turns on when you touch the cheek. This leads to accidental taps, turn off the sound or reset the call. The proximity sensor is a tiny but critical component that is responsible for the interaction of the device with the user at the time of the conversation.
When sensors are not working properly, they can be caused by software failure, physical contamination, or hardware failure. In MIUI and its successor HyperOS, sensor algorithms sometimes conflict with third-party applications or protective films. Understanding how this module works will help you choose the right method of solving the problem without resorting to expensive repairs.
In this article, we will take a look at all the possible causes of malfunction, from mundane dirt to complex calibrations, how to use hidden engineering codes for diagnosis and when it is really necessary to carry a device to a service center. Calibration of the sensor often solves the problem in a few minutes, if you approach the process correctly.
Principle of operation and main causes of failures
Most modern Xiaomi smartphones use infrared proximity sensors located at the top of the screen or in the display frame. They emit an invisible beam and read its reflection. If an object (your ear) is close, the beam reflects, and the system gives a command to extinguish the display. However, in budget models or when using protective glasses with a wide black bezel, the beam can be reflected from the film itself, creating a false positive.
There's also a software aspect to the sensor, and the operating system asks the sensor at a certain frequency, and if there's a heavy process going on in the background or there's a driver failure, the response to a change in lighting can be delayed, and calibration failure is one of the most common causes, especially after a device falls or an unskilled display change.
⚠️ Attention: A common cause of false positives is a poor-quality protective glass that covers the area of the sensor. If the glass has a black frame, make sure that it does not cover the sensor window.
Physical damage, such as impacts or moisture, can lead to oxidation of the contacts or displacement of the plume inside the housing. In such cases, software methods will be useless. It is also worth considering that in some models the sensor is combined with a front camera or speaker, which complicates diagnosis.
Basic diagnostics and sensor cleaning
Before we get to the complex settings, we need to rule out the trivial reasons. Often the problem lies in contamination of the top of the screen with greasy traces, dust or cosmetics. Even a thin film of dirt can scatter the infrared beam without letting it reflect correctly. Carefully wipe the area around the front camera and the speaker with a soft microfiber.
Check if you have a protective film or glass that has shifted over time on the screen. If you've recently changed the display or glass, the wizard may have accidentally damaged the sensor plume or stuck it poorly. Visual inspection will help identify obvious defects. If external factors are excluded, proceed to software testing.
- 🧹 Wipe the top face of your smartphone with an alcohol napkin to remove fat.
- 📱 Remove the protective glass and check the sensor without it.
- 🔄 Restart the device in Safe Mode to eliminate the impact of third-party applications.
- 🔦 Illuminate the sensor area with a flashlight to check the screen response (it should go out).
For a deeper check, you can use built-in diagnostics. Type ##6484## in the phone book to get into the CIT engineering menu. Select "Proximity Sensor" and put your hand to the top of the phone. The indicator should change from 5.0 to 0.0 (or vice versa, depending on the model). If there is no reaction, the problem is likely hardware.
Calibration of the proximity sensor through the engineering menu
If the sensor is physically functional but not working properly, it needs to be recalibrated, a procedure that trains the system to understand what counts as proximity and what counts as removal of an object. In Xiaomi smartphones, this can be done through the same engineering menu that was used to diagnose, and it is effective in 80% of software failures.
To start calibrating, open the Phone app and dial ##6484##. In the menu that opens, look for "Proximity Sensor." You'll see a numerical window. Put your phone on a flat horizontal surface, away from any objects, so that the sensor is clear.
☑️ Checklist before calibration
Press Calibration or Start. Don't touch your phone or breathe on it at this point. The system will read the baseline and set the thresholds to work. Once you're successful, the message will appear, "Calibrate Success." If the process fails, repeat the procedure again, making sure there's nothing disturbing the sensor.
⚠️ Warning: Do not calibrate in bright direct sunlight or under a high-powered lamp.
After a successful calibration, be sure to restart your smartphone, which is necessary to apply new parameters to the system. If the problem persists after the reboot, you may need to reset to factory settings or check for firmware updates. Resetting often eliminates software conflicts that interfere with the operation of sensors.
MIUI settings and the impact of third-party applications
The MIUI shell has many features that can conflict with the proximity sensor, such as pocket mode or various control gestures, which can intercept the screen, and some applications, especially callers and messengers, may have their own sensor settings, ignoring the system.
Check your call settings. Go to the Phone app, click on three dots or a gear, and find the Incoming Calls section. Make sure that the random tap lock function is active. Sometimes it helps to turn off and re-enable this option. It's also worth checking the permissions for the Phone app in the settings section.
- 📞 Remove newly installed apps for calling or recording conversations.
- ⚙️ Check system updates in the Settings section → The phone.
- 🚫 Turn off the theme if it was recently installed.
- 📲 Reset the settings of the phone application through the application menu.
Third-party launchers and themes can change the system files that run the interface. If a problem occurs after you install a new theme, bring back the standard design. Often users don't associate visual changes with functional failures, but in the Xiaomi ecosystem, this is quite real.
Hardware problems and replacement of components
When software methods fail, you have to consider a physical breakdown, and the proximity sensor can fail due to impact, vibration, or moisture. In modern smartphones, it's often embedded in a display plume or in a separate top speaker module, and replacing these components requires precision and special tools.
If you've had experience disassembling the equipment, you can try to gently disconnect and reconnect the sensor plume, and sometimes the oxidized contacts can be reconstituted with alcohol, but if the sensor itself is burned, only a replacement will help. The cost of the part is usually low, but the work of the master can cost more, especially on models with a high-performance model. AMOLED-screens where replacement requires re-painting.
| Symptoms. | Probable cause | Method of decision |
|---|---|---|
| The screen doesn't go out when you talk. | Pollution or calibration failure | Cleaning and calibration at CIT |
| The screen goes out immediately upon lifting. | Safety glass or false alarm | Removing glass, checking the plume |
| The screen flashes while talking | Unstable contact or software | Reconnecting the plume, resetting the software |
| The sensor doesn't respond at all. | Trail break or sensor death | Replacement of module in the service |
When replacing a display with a non-original one, there are often problems with sensor compatibility. Cheap copies of screens may not have calibration data or have a different type of sensor, in which case it helps to transfer the old sensor to a new screen or use special patches in the firmware (requires root rights).
Risks of self-replacement
Use of third-party applications for management
If you can't solve the problem with regular tools, you can use third-party software from Google Play. There are many utilities that force the proximity sensor to control the proximity sensor, ignoring system errors, and these applications are especially useful on older models where support is no longer updated.
One of the popular solutions is the Proximity Sensor Reset & Fix app, which allows you to reset the sensor cache and force calibration, and there are callers with their own sensor engine that can bypass bugs in a standard phone app, but it's worth remembering the security of personal data.
- 📲 Download the sensor diagnostics app from a verified source.
- 🔒 Check the permissions requested by the application (access to the phone is mandatory).
- ⚙️ Use the “Force Calibration” function in the application settings.
- 🗑️ Remove the application after successfully solving the problem to save resources.
Some users use apps that lock the screen on a timer or volume button, turning off the proximity sensor completely. It's a crutchy but workable solution for those who are used to answering calls with a button or headset. Disabling the sensor can be a temporary measure before buying a new phone.
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Useful tip: Before installing third-party applications, back up contacts and important data, as some utilities require deep system access rights.
Prevention and proper operation
To ensure that the proximity sensor lasts long and fails, it is important to follow simple rules of operation: regularly clean the top of the smartphone from contamination; avoid using covers and glasses that overlap the working area of the sensor; protect the device from shocks and sudden temperature changes that can lead to detachment of the plumes.
Update your software on time. With newer versions of MIUI and Android, developers often fix hardware bugs. If you notice that a problem has disappeared or appeared after an update, report it to support or community forums.
⚠️ Warning: Do not use aggressive chemistry to clean the screen. Alcohol-containing solutions can damage the oleophobic coating and the sensor's plastic lens.
Proper operation extends the life of not only the sensor, but the entire smartphone. Keep track of the connectors and buttons. Comprehensive care of the device reduces the risk of critical malfunctions at the most inopportune time.
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Regular cleaning of the speaker and the top frame of the phone is the best prevention of problems with the proximity sensor.