Calibration of the proximity sensor on Xiaomi Poco X3 NFC: a complete guide with secrets

The proximity sensor in the Xiaomi Poco X3 NFC is a small but critical component that is responsible for turning off the screen during a phone call. When it doesn't work properly, you run into annoying problems: the screen doesn't go out when you bring the phone to your ear, random taps during calls, or, conversely, a black screen that doesn't want to turn back on, and most often the fault is the calibration of the sensor - a malfunction in its software settings, not a physical breakdown.

Many users mistakenly think that you need to take your phone to a service center or buy a new module to solve a problem. In fact, 80 percent of the time, software calibration helps, which can be done on your own in 5-10 minutes. In this article, we will analyze all working methods, from standard MIUI tools to hidden engineering codes and manual testing through ADB. You will also learn how to check whether the sensor is really to blame, rather than, for example, a protective glass or a case.

Before you start calibrating, make sure that the problem is not caused by mechanical interference.

• 🔍 Case or bumper – some models overlap the sensor area (usually located next to the front camera).
• 📱 Protective glass – if it is glued curved or too thick, the sensor may not work.
• 💦 Moisture or dirt – dust entering the speaker/sensor often causes false positives.

1.How do I know if the proximity sensor is faulty?

Before you calibrate the sensor, you need to confirm that it's the problem, and the symptoms of the malfunction are often confused with firmware glitches or hardware defects, and here are the key signs of proximity sensor failure:

• 📞 The screen does not go out when you bring the phone to your ear during a call (the risk of accidental pressing).
• 🖤 The screen remains black after the conversation ends and does not respond to pressing.
• 🔄 The autoturn of the screen is unstable (although the gyroscope is serviceable).
• 📊 In the engineering menu (#6484##) the sensor shows inadequate values (for example, always 0 or 5).

If any of these symptoms are present, it's likely that the sensor needs calibration, but first, rule out false positives.

1. Call your phone and check if the screen goes out when you hold your palm (not necessarily your ear) to the top of the display.
2. Try removing the cover and repeat the test.
3. Launch the camera and cover the sensor area with your finger – if the screen darkens, the problem is precisely in it.

💡

If the sensor only works when pressed hard, it is likely to be contaminated. Try to gently clean the area around the front camera with compressed air (do not use wet wipes!).

2. Standard calibration through MIUI settings

Xiaomi Poco X3 NFC based on MIUI 12/13/14 has a built-in tool for calibrating sensors, but it is hidden in the depths of the menu.

1. Open the Settings. → The phone.
2. Tap 5-7 times on the MIUI version until the notification “You became a developer” appears.
3. Return to the main settings menu and select Additional → For developers.
4. Find the Sensor Calibration section (may be called Sensor Calibration in English firmware).
5. Select the Approach Sensor and follow the instructions on the screen (usually you need to put the phone on a flat surface and wait for the process to be completed).

If there's no Sensor Calibration, then your version of MIUI doesn't support this method, so move on to the next method.

Make sure the battery is charged more than 30 times%|

Close all background applications |

Remove the cover and protective glass (if any)|

Check that the sensor is not contaminated.-->

3. Calibration through the engineering menu (USSD codes)

The engineering menu is a hidden tool for diagnosing and tuning hardware components. On the Poco X3 NFC, it opens with special codes. Attention: don't change the other options on this menu unless you're sure they're there!

For calibration of the proximity sensor:

1. Open the Phone app and enter the code ##6484## (some firmware may run ##2664##).
2. Select Proximity Sensor (approximation sensor).
3. A graph or numerical values (usually 0 to 5) will appear on the screen. Normal values at rest: 5, as the object approaches: 0.
4. If the values do not change or show incorrect data, press Calibrate.
5. After calibration, restart the phone.

If there is no calibration option in the engineering menu, try the alternative code:

##4636##

→ Testing of equipment → Sensors. → Proximity Sensor.

Manual calibration via ADB (for advanced users)

If standard methods don't work, try resetting the sensor via the Android Debug Bridge (ADB), which requires a computer and basic command line knowledge.

Instructions:

1. Enable USB debugging in the developer settings (Settings → Additional → For developers).
2. Get Poco on. X3 NFC computer-to-computer USB-cable (original!).
3. Open the command prompt (Windows) or terminal (macOS/Linux) and type: Adb devices Make sure your phone appears in the list.
4. Execute the command to reset the sensor calibration: adb shell settings put system proximity_offset 0
5. Reboot the phone.

If the sensor is still not working properly, try manually setting the thresholds (root required):

adb shell su -c "echo 0 1 2 3 4 5 6 7 8 9 10 > /sys/class/sensors/proximity/prox_cal"

💡

ADB-The method is the most reliable, but it requires caution. The wrong commands can cause the system to fail. If you're not sure what you're doing, skip this step.

5. Verification of the sensor with third-party applications

If the built-in MIUI tools don't give a clear picture, use third-party diagnostic tools to show real-time sensor values.

Top.-3 testing-in:

• 📊 CPU-Z — The sensors are all in the vicinity sensor.
• 🔧 Sensor Test – visualizes the work of sensors with graphs.
• 🛠️ Phone Doctor Plus – conducts a full diagnostics of hardware components.

How to use:

1. Install one of the applications (e.g., Sensor Test).
2. Run the proximity sensor test.
3. Put your hand to the top of the screen, and the values should change from 5 (no object) to 0 (object detected).
4. If the values do not change or jump randomly, the sensor needs to be replaced.

Hardware causes of sensor malfunction

If the software calibration didn't work, the problem could be a physical breakdown of the sensor or associated components, and the most common causes are:

• 💥 Mechanical damage - phone fall, hit on top of body.
• 💧 Moisture intake - oxidation of the sensor or plume contacts.
• 🔌 Disconnection of the plume – often occurs after disassembling the phone.
• 🛠️ Sensor wear – over time, sensitivity decreases (especially with active use).

How to diagnose a hardware malfunction:

1. Check if the sensor is responsive to any objects (even non-metallic ones).
2. Light a flashlight into the sensor area – if it’s infrared, you’ll see a faint glow.
3. Take the phone apart (if you have experience) and check the integrity of the plume.

⚠️ Note: If the sensor does not respond fully to calibration and tests, and the values in the engineering menu are always 0 or 255, most likely a replacement module is required. X3 NFC The proximity sensor is combined with the front camera, so you'll have to change the entire unit: ~1500–2500 rubles.

7. Frequent calibration errors and how to avoid them

Many users make the same mistakes that make calibration ineffective. Here's what you can't do:

• 🚫 Using non-original chargers during calibration – this can cause sensor malfunctions.
• 🚫 Interrupt the calibration process (e.g., exit the engineering menu before completion).
• 🚫 Calibrate the sensor with a discharged battery (less than 20%) - this can lead to incorrect settings.
• 🚫 Change the sensor settings manually (via ADB or engineering menus without knowing the exact parameters.

Also note:

• 📱 The temperature of the phone - if Poco X3 NFC overheating, sensors may work unstablely.
• 🔄 Version of firmware - on some custom assemblies MIUI calibration may not be maintained.
• 🛠️ root rights – some methods (e.g. editing files in the /sys/class/sensors/) root.

⚠️ Note: After calibration through ADB Or the engineering menu, make sure to restart the phone, otherwise the settings may not take effect and the sensor will continue to glittle. MIUI — Sometimes system updates reset calibration.

FAQ: Answers to Frequent Questions