How to check the proximity sensor on Xiaomi Poco F3: from diagnosis to repair

The proximity sensor in the Xiaomi Poco F3 is a small but critical component that is responsible for turning off the screen during phone calls. When you hold the phone to your ear, the sensor registers the obstacle and extinguishes the backlight, preventing accidental pressing and saving battery power. However, over time, this module can fail: the screen stops turning off when calling, reacts with a delay or, conversely, goes out for no reason. These symptoms are not only annoying, but also interfere with normal smartphone use.

In this article, we’ll look at 5 reliable ways to test the proximity sensor on the Poco F3, from built-in MIUI tools to third-party applications and hardware tests. You’ll learn how to distinguish a software failure from a physical failure when a reboot is enough and when it’s time to bring your phone to service. All methods are tested on current firmware versions and don’t require root rights or device disassembly.

Signs of malfunction of the proximity sensor

Before you start diagnosing, it is important to make sure that the problem is really related to the sensor, not software settings or mechanical damage to the screen.

• 📱 The screen does not go out when you hold the phone to your ear during a ringing (even if you close the top with your palm).
• ⏳ Reaction delay: The screen is turned off by 2-3 seconds after the application, although earlier it worked instantly.
• 🔄 Spontaneously turning on/off the backlight during a conversation, as if the sensor “twitches».
• 📵 The screen goes out for no reason during normal use (for example, when reading messages), although there are no obstacles nearby.
• 🔊 The sound switches to the speaker instead of the spoken one, even though the phone is lying on the table.

If at least one of these signs is on the regular, the Poco F3 approach sensor needs to be checked, but don't be quick to blame the iron: 30 percent of the time, system settings or third-party applications that block the sensor are to blame, for example, some launchers or battery-saving programs may conflict with the sensors.

Method 1: Test through the engineering menu (code ##6484##)

The fastest and most accurate way to check the proximity sensor is to use the hidden MIUI engineering menu, which is available on all Xiaomi smartphones, including the Poco F3, and does not require additional software installation.

1. Open the Phone app and enter the combination: ##6484##.
2. The Hardware Test menu will appear on the screen. Select Proximity Sensor.
3. Place your hand or an opaque object (such as a book) above the top of the screen where the sensor is located.
4. The screen should show the values 0 (if the sensor is closed) and 5 (if the numbers are open).

🔹 What do the numbers mean?

• 0 - the sensor is closed (obstacle detected).
• 5 - the sensor is open (no obstacles).
• - or no response - the sensor is not working.

Close all background applications

Make sure there is no protective film or cover on the screen.

Use an opaque object (hand, book)

Repeat the test. 2-3 time-in-time-->

⚠️ Warning: If the engineering menu doesn't open, check if it's blocked by antivirus or Google Play Protection. MIUI You may need to enter a password: by default it is 1234 or 0000.

Method 2: Checking with Sensor Test

If the engineering menu is not available or you want a more detailed diagnosis, use the third-party Sensor Test app (available on Google Play), which shows data from all sensors on your smartphone, including approximations, lights and an accelerometer.

1. Download and install the Sensor Test.
2. Launch the app and find the Proximity tab.
3. Cover the sensor with your palm - the value should change from Far (far) to Near (close).
4. Remove your hand, the status should go back to Far.

📊 Unlike the engineering menu, the Sensor Test shows a real-time graph of the sensor's response, which helps detect sensor twitching or unstable readings, for example, if the graph is constantly jumping between Near and Far without your intervention, the sensor requires replacement.

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If the app doesn’t see the proximity sensor, check if it’s disabled in the developer settings. Go to Settings → About Phone → MIUI version and click on this item 7 times to activate the developer mode.

Method 3: Diagnostics through call settings

Sometimes the problem isn't with the sensor itself, but with the phone settings, for example, when you update your MIUI or reset your settings, the setting that turns off the screen during a call might get lost.

1. Open Settings → Applications → Phone → Call settings.
2. Find the option to turn off the screen when approaching (or similar in meaning).
3. Make sure the switch is active (slider in position On).

If the option is disabled, turn it on and check the sensor during the test call. Also, pay attention to the section "Additional settings" - there may be a Sensitivity item that should be set to High.

⚠️ Note: Some custom firmware (e.g. Pixel Experience or LineageOS) may not have these settings or may be called otherwise.

Method 4: Hardware inspection (without disassembly)

If software tests show that the sensor is working but problems remain, mechanical factors may be to blame:

• 🧴 Sensor contamination (dust, fat, film glue residues).
• 📱 Damage to the plume after falling or repairing.
• 🔋 Overheating of the processor, due to which the sensor is turned off.

To rule out these reasons:

1. Clean the sensor: wipe the top of the screen (near the speaker) with a cotton swab dipped in alcohol. Do not use abrasive materials!
2. Check without a case: Some cases with metal inserts can shield the sensor signal.
3. Cool your phone: If the Poco F3 overheats (like after games), let it cool for 10-15 minutes and repeat the test.
4. Call the plume, if the phone falls, the sensor contact may have gone, and that means you need to disassemble the device or contact the service.

Critical information: On the Poco F3, the proximity sensor is combined with the light sensor in the same module, and if both sensors are not working, the problem is in the plume or module itself, and you need to replace it.

Method 5: Resetting and calibrating the sensor

If the sensor responds to the tests but is unstable (e.g., it works again), try resetting it or calibrating it.

1. Reset the settings of the Phone application: Settings → Apps → Phone → Storage → Reset the settings
2. Calibrate through the engineering menu: ##6484## → Proximity Sensor → Calibrate (If there is no Calibrate option, then calibration is not supported on your firmware.)
3. Reset all settings (if nothing worked): Settings → About Phone → Resetting → Reset network settings

🔧 After reset, check the sensor during the 1-2 If the problem persists, it will likely require a replacement module. ~1 500–2 500 rouble 2026 year), depending on the region.

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If the sensor doesn't respond to any of the tests, but it appears to be working in the engineering menu, the problem may be the firmware. Try updating MIUI to the latest version or rolling back to stable.

Frequent questions about the proximity sensor on the Poco F3