How to independently check the proximity sensor on Xiaomi Poco X3: from test codes to hardware diagnostics

The Xiaomi Poco X3 is one of the most popular smartphones in the Poco lineup, but even it is not immune to hardware problems. One of the frequent malfunctions is the proximity sensor, which is responsible for turning off the screen during a phone conversation. If your screen does not go out when you bring the phone to your ear or, conversely, does not turn on after a call, the problem may lie in this sensor.

In this article, we’ll look at 5 working ways to test the proximity sensor on the Poco X3, from simple tests using an engineering menu to third-party diagnostics and manual hardware checks, and learn how to distinguish a software failure from a physical failure, and what to do if the sensor is truly faulty.

Important: Before starting a diagnosis, make sure that your smartphone does not have a protective film or case that covers the sensor area (usually located at the top of the screen next to the speaker), often the problem lies in the mechanical obstacle, and not in the sensor itself.

1. Checking the proximity sensor through the engineering menu (test codes)

The fastest way to diagnose is to use hidden test codes that open up access to hardware tests. On Xiaomi Poco X3, a combination of:

##6484##

Once you enter this code, you will open the MIUI Test menu (or Manual Test in some versions of the firmware).

1. Select Proximity Sensor (approximation sensor).
2. Bring your hand or object to the top of the screen (where the sensor is located).
3. The screen should show a value of 0 (if the sensor is closed) or 5 (if the sensor is open).

If the values do not change or if the Failed error is displayed, this indicates a fault of the sensor or its drivers. On the Poco X3 with MIUI 12.5+ firmware, the test code may not work - in this case, use an alternative method (Section 2).

⚠️ Note: Not all test codes run on custom firmware (e.g. LineageOS or Pixel Experience).If nothing happens after you enter the code, check the software version in Settings. → The phone. → Version. MIUI.

2. Diagnostics through the application "Sensor Test" (without root)

If the engineering menu is not available, use a third-party app, one of the most reliable is the Sensor Test (available on Google Play), which does not require root rights and shows data from all sensors in real time.

How to check:

1. Install the Sensor Test application.
2. Run it and find the Proximity tab.
3. Put your hand in the sensor, the value should change from 5.0 cm (far) to 0.0 cm (close).

If the values are static or N/A is displayed, this may mean:

• 🔧 Software failure – sensor driver fails to respond.
• 🛠️ Hardware failure – sensor physically damaged.
• 📱 Firmware conflict – especially relevant after the update MIUI.

Make sure there is no film or glass on the screen that covers the sensor.|

Close all background applications (especially SEOs and antiviruses) |

Check that the screen brightness is set to 50% or higher |

Turn off the energy saving mode in the settings-->

3. Manual check by call (without applications)

If you don't want to install third-party software, you can check the sensor in combat, during a real call.

1. Call another phone or use a voice call (such as via WhatsApp).
2. Hold the Poco X3 to your ear, and the screen should go out instantly.
3. Take the phone away, the screen should turn on immediately.

If the screen:

• 🔄 It does not go out – the sensor does not detect the approach.
• 🖥️ Not turned on after withdrawal - the sensor "sticks" in the state "closely".
• ⚡ Flashes or spontaneously turns on / off - a failure in the operation of the sensor or its drivers is possible.

This method does not provide accurate technical data, but helps to identify a problem in everyday use. If a malfunction is confirmed, move on to a deeper diagnosis (sections 4-5).

⚠️ Note: On some Poco firmware X3 There is a bug in which the screen does not go out if the mode in the pocket is turned on during the call (Settings) → Screen. → Pre-test, turn off this option before the test.

4. Check through ADB (for advanced users)

If standard methods don't work, you can use ADB (Android Debug Bridge) to read raw data from the sensor, which requires connecting the phone to a computer, but gives you the most accurate information.

Instructions:

1. Install ADB Tools on your PC.
2. Turn on USB Debugging on Poco X3 (Settings → About Phone → MIUI Version → 7 times click on version, then go back to Settings → Additional → For Developers).
3. Connect the phone to the PC and type in the command line:

adb shell dumpsys sensorservice

In the conclusion, look for the Proximity Sensor unit.

mPendingEvents= {




0: [type=8, sensor=5, accuracy=3, timestamp=123456789, values=[0.0]]




1: [type=8, sensor=5, accuracy=3, timestamp=123456790, values=[5.0]]




}

Here:

• values=[0.0] - the sensor is closed (obstacle detected).
• values=[5.0] - the sensor is open (no obstruction).

If the values do not change when you raise your hand or if accuracy=0 is displayed, the sensor is defective.

5. Visual inspection and inspection of sensor plume

If software tests show a malfunction but you're not sure why, check the hardware. On the Xiaomi Poco X3, the proximity sensor is located at the top of the display module and connected via a flexible plume.

To verify:

1. Remove the back cover (need a mediator and a hair dryer to soften the glue).
2. Disconnect the battery (required!).
3. Find the plume that goes from the display module to the motherboard - it has a sensor.
4. Check the plume for breaks, oxidation, or poor contact.

⚠️ Attention: Disassembly of Poco X3 without experience can damage the display plume or break off the contacts of the battery. If you are not sure of your skills, contact the service center. The cost of replacing the proximity sensor in the official Xiaomi SC is from 800 to 1500 rubles (2026).

💡

Before disassembly, take a picture of the location of all the plumes and screws - this will help to assemble the phone without unnecessary details.

6. Alternative causes of malfunction (if the sensor is in good working order)

In 30 percent of cases, the problem is not the sensor itself, but the concomitant factors.

• 📲 A protective glass or film — if it covers the sensor area (usually to the left of the speaker), the sensor will not work properly.
• 🔋 Energy saving mode - in some versions MIUI It turns off the sensors to save charge. → Battery → Energy saving regime.
• 📱 Application conflict – Optimizers (such as Greenify) or launchers can block the sensor. Launch the phone in Safe Mode (hold the switch off button). → "Safe mode" and repeat the test.
• 🔄 Failure after the update – if the problem appeared after the update MIUI, Try to roll back to the previous version or reset your settings.

If none of these methods worked, there are two options:

1. Phone flashing – sometimes helps to reset driver errors.
2. Replacement of the display module - the proximity sensor soldered into it and is not sold separately.

💡

On the Poco X3, the proximity sensor fails 90% of the time due to mechanical damage (fall, impact) or moisture under the plume. Software failures are less common and are usually solved by resetting or flashing.

FAQ: Frequent questions about the proximity sensor on the Poco X3