The problem with the proximity sensor on Xiaomi and Poco smartphones is one of the most common complaints of users, especially on models with a high-performance sensor. IPS-screens such as Poco X3 Pro. The essence of the problem is that during a conversation, the phone does not turn off the screen when you bring it to the ear, which leads to accidental pressing of the cheek, or, conversely, extinguishes it too early. The owners of flagships and public sector employees face this equally often, and it is impossible to ignore this defect, since it directly affects the comfort of communication.
Diagnosing a proximity sensor is the first step to take before going to a service center. Often the problem is not a physical sensor failure, but a software failure, contamination, or miscalibration. In this article, we will detail all the verification methods available, from built-in system tests to hidden engineering menus that will help identify the true cause of the malfunction.
Modern smartphones use a combination of infrared radiation and software analysis to determine the distance to the object. On the Poco X3 Pro, this sensor is located at the top of the display, hidden under the protective glass. If a software check shows an error, it could mean that the sensor is filled with dust or has a hardware defect of the plume, which will require deeper intervention.
Symptoms of malfunction and primary diagnosis
Before running complex tests, you should look at the obvious signs of malfunctioning. Sensor malfunctions often manifest in the most trivial use cases that users may initially ignore. Understanding these symptoms will help you formulate the problem accurately when you contact a specialist or when you search for a solution yourself.
The main indicator of the problem is the behavior of the screen during an incoming or outgoing call. If the phone is held to the ear, the screen continues to glow and you accidentally press the volume or reset button, then the sensor does not see the object. The reverse situation, when the screen goes out immediately after the start of the conversation without touching the head, also indicates a malfunction of the infrared sensor.
Another sign may be strange behavior when watching videos or reading horizontally. Some applications use sensor data to automatically turn off the screen if you close the top with your palm. If the screen goes out when you lightly touch the top frame, or, conversely, does not respond to a complete overlap in this area, this is an alarm.
⚠️ Note: If the screen goes out chaotically even without overlapping the top, this may indicate a short circuit in the plume or oxidation of contacts after moisture hits.
It's also worth checking if the sensor is interfering with the protective glass or film. Cheap accessories often have a black edging that covers the area of the sensor. Remove the protective coating and repeat the test to rule out this trivial but common cause.
Use of the built-in CIT engineering menu
The most reliable and quickest way to test the health of all smartphone modules is to use the built-in CIT (Calibration and Information Test) engineering menu, a tool created by Xiaomi engineers specifically for diagnostics of devices in the factory and in authorized service centers, access to which does not require root rights or install third-party software.
To get into the test menu, open the standard Phone app and type a special code. Dial the combination ##6484##. If the code is entered correctly, the system will automatically switch you to the CIT menu, which presents a complete list of all the components of the device.
In the list that opens, you'll find the item associated with the proximity sensor, which is usually called ProxSensor or Approximation Sensor. Click on this to run the test, and you'll see a screen with a numerical value and instructions.
- 📏 Hold your hand to the top of the screen (where the speaker is located) at a distance. 1-2 The value should change (usually with the 5.0 on 0.0 vice versa).
- 👁️ Remove your hand – the readings should return to the original state instantly.
- 🔄 Repeat the action several times to ensure the stability of the sensor response.
If the values change clearly and without delay, then the hardware is good, and the problem should be looked for in the software or calibration, and if the test screen does not respond to hand movements, or the values "jump" chaoticly, this indicates a physical breakdown.
Verification through the Developer Mode
If for some reason the engineering menu code is not working or you want more technical information, you can use the developer mode, which allows you to see raw sensor data in real time, which is useful for deep diagnostics.
To activate Developer Mode, go to Settings → About Phone and click 7 times in a row on the MIUI Version field. After the “You are a developer” message appears, return to the main settings menu, select Additional → For Developers. Find “Enter Test Mode” or run the test through the Recovery Menu if such an option is available in your firmware version.
However, the easier way to do this in developer mode is to check logs or use ADB, but for the average user it will be easier to check the work through the standard testing menu, which we have already considered. However, in developer mode you can try to reset the sensor settings, if this option is available in your version of Android.
It is important to understand that the developer mode gives access to critical system settings. Do not change the settings that are not sure about, as this can lead to unstable operation of the operating system.
What to do if the CIT code does not work?
Sensor calibration procedure
If tests show that the sensor is responding but not correctly (e.g., only working close to the screen), calibration is necessary. Calibration is the process of setting thresholds at which the system thinks the object is close. This is a software procedure that often solves problems after replacing the screen or glass.
To perform the calibration, log back into the CIT engineering menu using code ##6484##. Find ProxSensor. Some versions of the interface will have a Calibration or Calibration button after entering the test. If not, calibration can be done automatically when you select a menu item.
The process is this: you're going to be asked to remove all the objects from the screen, and then you're going to have to close the sensor with your palm, and you're going to have to follow the instructions on the screen, and once you've done that, the phone can automatically reboot.
☑️ Checklist before calibration
There is also a method of calibration through the hidden engineer menu, available in code ##64663## (not working on all versions of MIUI), where you can find the Proximity sensor calibration and press the Start button. It is important not to move the phone or close the screen during the process until the corresponding requirement appears.
⚠️ Note: Do not calibrate if the screen is thick protective glass. After calibrating without glass, the phone will work incorrectly with the glass, and vice versa.
Hardware causes and physical examination
When software methods fail, you need to consider a physical malfunction. In the Poco X3 Pro, as in many modern smartphones, the proximity sensor is integrated into the display plume or located on a separate board under the screen, which makes it vulnerable to falls and impacts.
One of the common reasons is that the rubber light shielding gasket has been unplugged, and this little black piece directs the infrared beam straight forward, and if it's shifted or lost, the beam bounces off the phone's internal components, and the sensor thinks it's in front of an object, locking the screen permanently.
It's also worth checking for cracks on the screen at the top, and even a micro-crack that's invisible to the eye can distort infrared radiation, and moisture trapped inside the housing often oxidizes the plume contacts, leading to periodic failures.
Visual inspection will require disassembly of the device, which requires special skills and tools, and if you are not confident in your abilities, it is better to entrust this procedure to professionals so as not to damage the fragile display module.
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Before disassembling the phone, always completely discharge the battery to 0% or turn off the battery plume immediately after opening the case to avoid short circuit.
Comparison of diagnostic methods
For ease of perception, we have systematized the basic methods of checking into a table, which will help you choose the most suitable option depending on your situation and level of technical training.
| Method of verification | Difficulty | precision | Skills required |
|---|---|---|---|
| Surveillance in the bell | Low. | Medium | Not required |
| CIT's Engineering Menu | Low. | Tall. | Basic |
| Apps from Play Market | Medium | Tall. | Installation of PO |
| Disassembly and inspection | Tall. | Maximum | Professional |
Use third-party apps from Google Play, such as “Proximity Sensor” Reset/Fix» Or Sensor Test, which can give you more information, but they don't always have access to Xiaomi's deep system settings. CIT The gold standard of diagnosis.
If none of the software methods has identified the problem and the symptoms persist, with a 90% probability, a replacement of the plume or screen module is required. In the Poco X3 Pro, the sensor is often assembled with the display, which increases the cost of repair, but guarantees the result.
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90% of proximity sensor problems are solved by CIT calibration or glass replacement, and only 10% require hardware components to be replaced.