How to independently check the proximity sensor on Xiaomi: from codes to disassembly

Approximation sensor in smartphones Xiaomi, Redmi and POCO — It's a small, but critically important element that's responsible for turning off the screen during a conversation, and when it goes down, you're faced with annoying problems. The screen goes out arbitrarily, doesn't respond to touch when you ring, or, conversely, stays active in your ear, causing random taps. 80% of the time, users mistakenly blame the firmware or touchscreen, even though the proximity sensor is the one to blame.

This article will help you diagnose a malfunction accurately without going to a service center, and we'll go through all the methods of verification, from hidden engineering codes to hardware testing with disassembly of the housing. You will learn how to distinguish a software failure from a physical sensor breakdown, which Xiaomi models are more likely to suffer from this problem (spoiler: Redmi Note 10 Pro and the other two models are more likely to suffer from this problem). POCO X3 Pro leads on complaints, and what to do if the sensor is really broken. FAQ answering the most common questions, such as whether it is possible to calibrate the sensor yourself and how much it costs to replace it.

1. Signs of a failure of the proximity sensor

Before you check the sensor, make sure it's the one that's the problem, and here are the key symptoms that indicate sensor malfunctions:

• 📱 The screen goes out when you call, even if you don’t bring the phone to your ear (or vice versa – does not go out when you bring it to your ear).
• 🔄 Sensor is triggered with a delay: the screen is turned on only through 2-3 seconds after the phone was withdrawn.
• 🎯 The touchscreen is blocked randomly, such as when watching a video or in games, if the hand covers the top of the screen.
• 🔦 In the dark, you can see that the sensor (a small window next to the front camera) does not glow or flicker.
• 📞 After updating MIUI The screen stopped turning off during calls (a common problem after switching to the screen) MIUI 14+).

If any of these signs are familiar, the sensor needs to be checked, but first, rule out false positives.

• 🧲 Check if there are magnets or metal objects nearby (they can affect the sensor’s performance).
• 📱 Make sure there is no protective film or glass on the screen covering the sensor area.
• 🔄 Reboot your phone - sometimes glitches MIUI It is solved by a banal reboot.

⚠️ Attention: On Xiaomi models 12T Pro and Redmi. K50 The Ultra proximity sensor is aligned with the light sensor, and if you don't have the brightness of the screen adjusted at the same time, it can be a complex problem.

2. Check the sensor through the engineering menu (codes ##)

The fastest way to diagnose is to use hidden service codes, which work on all Xiaomi smartphones regardless of model and version. MIUI. You don’t need root rights or special apps.

Open the Phone app and enter one of these codes:

• ##6484## is a test of the proximity sensor (on some models).
• ##4636## → Phone information → Scroll down to the Sensor Block.
• ##2664## - Alternative sensor test (works on the sensors) POCO old Redmis).

Once you enter the code, you'll see a screen with a graph or a digital value, and here's how to interpret it:

On some firmware (e.g, MIUI Global 14.0.4) can block the engineering menu, in which case use an alternative method - applications for testing sensors.

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If the ##4636### code doesn’t work, try typing it into the Calculator app (yes, that’s no joke – it works on some Xiaomi models!).

3. Testing with third-party applications

If the engineering menu is not available or you want more detailed information, install one of these apps from Google Play:

• 📱 Phone Doctor Plus – Shows the status of all sensors, including approximations, with real-time visualization.
• 🔍 Sensor Test – a minimalist tool with graphs and digital values.
• 🛠️ CPU-Z → Sensors tab – displays the sensor’s technical data (model, range, current state).
• 📊 DevCheck – detailed information about the hardware, including the type of proximity sensor (e.g, STK3338 or APDS-9960).

How to check the sensor in Phone Doctor Plus:

1. Open the app and select Sensor Test.
2. Find the Proximity Sensor line.
3. Close the sensor with your hand – the status should change from Far (far) to Near (close).
4. Remove your hand - status should return to Far.

If the status is unchanged or the application shows an error (e.g. Sensor not available), this may mean:

• 🔌 Sensor is physically disabled (problem with plume).
• 📱 Software failure after update MIUI.
• 🛠️ The sensor is contaminated or closed with protective glass.

Remove the phone case|Wipe the sensor area with a dry wipe|Turn off the energy-saving mode.|Close all background applications-->

4. Testing of the sensor without software (mechanical test)

If you don't have access to an engineering menu, or you don't want to install third-party apps, you can physically check the sensor. You only need a hand and a light source.

Step 1: Visual verification

Put a flashlight on the top of the screen (near the front camera).

• 🔦 Two small windows: one for the proximity sensor, the second for illumination.
• 💡 When you bring your hand to the proximity sensor, it should flicker slightly or change color (this is an infrared LED, invisible to the eye, but some cameras fix it).

Step 2: Test with a bell

1. Call your phone from another device.
2. Take the call and hold your hand to the top of the screen (without closing the microphone!).
3. The screen should go out in 0.3-0.5 seconds.
4. Remove your hand, the screen should turn on immediately.

Step 3: Sensitivity testing

If the screen goes out only when the sensor is completely closed (for example, with the palm of your hand), but does not respond to a slight approach, this is a sign of contamination or wear of the sensor.

⚠️ Note: On Xiaomi Mi 11 and newer models, the proximity sensor can be hidden under the display (Under-Display Sensor technology.

5. Diagnostics with disassembly of the phone (for experienced users)

If all previous methods have failed and the sensor is clearly not working, you can test it hardwarely, which requires accuracy and is only suitable for those who are willing to risk the warranty (if it is still valid).

You'll need:

• 🔧 Set of screwdrivers (star) T3, T4).
• 🧲 Plastic blade for opening the body.
• 🔍 Loop or flashlight (small sensor, easy to miss).
• 📸 Phone camera for fixing the location of plumes.

Step-by-step:

1. Turn off the phone and remove it. SIM-map.
2. Heat the back cover with a hairdryer (60–70°C) to soften the glue.
3. Carefully tuck the lid with a plastic spatula, starting at the bottom edge.
4. Unscrew the screws that hold the metal plate over the battery.
5. Find the proximity sensor plume – it goes from the top of the motherboard to the front camera.
6. Check if the plume has moved away from the connector. If so, gently plug it back in.
7. Examine the sensor itself for contamination or physical damage (cracks, oxidation).

If the sensor is externally serviceable but does not work, the problem may be:

• 🔌 Damaged plume (check for tears).
• 📱 Faulty motherboard (requires diagnosis in the service).
• 🔄 Firmware failure (try resetting or reflashing your phone).

Calibration of the proximity sensor (if it is not working correctly)

Sometimes the sensor isn't broken, it's just calibrated. This often happens after the phone drops, updates. MIUI Or resetting the settings, and calibration can get it back to normal.

Method 1: Through the Engineering Menu

Enter the code ##6484## and select Proximity Sensor Calibration. Follow the instructions on the screen - usually close the sensor with your hand, wait for the signal, and then remove your hand.

Method 2: Using the application MIUI Hidden Settings

1. Download the app from Google Play (required) MIUI 10+).
2. Open the Sensors section.
3. Find Proximity Sensor and press Calibrate.
4. Hold and remove your hand from the sensor 3-5 times as indicated in the instructions.

Method 3: Manual calibration (for advanced users)

If standard methods do not help, you can calibrate the sensor through ADB:

adb shell settings put system proximity_delay 100


adb shell settings put system proximity_offset 0

These commands reset the sensor's delay and offset. After you type in, restart the phone.

⚠️ Note: On Xiaomi 13 Pro and Redmi models K60 manual calibration may reset after update MIUI. If the problem comes back, repeat the procedure or roll back the firmware to the previous version.

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Calibration only helps with software failures, and if the sensor is physically damaged (crack, oxidation, plume break), the calibration will not work, either repair or replacement.

7 What to do if the sensor is broken: repair or replacement

If all tests show that the sensor is faulty, you have three options:

The cost of the spare part depends on the model:

• 📱 Redmi Note 10/11: sensor + plume — ~500 ₽.
• 📱 Xiaomi 12/13: sensor-and-camera — ~1 500 ₽.
• 📱 POCO F3/F4: sensor — ~400 ₽.

Where to buy spare parts:

• 🛒 AliExpress is cheaper but long (2-4 weeks of delivery).
• 🛒 Beru.ru or Ozon – faster, but more expensive by 20-30%.
• 🛒 Local parts stores (search for “approximation sensor [phone model]” on request]»).

If you want to change the sensor yourself, you should:

• 📸 Take a picture of all the plumes before disconnecting.
• 🔧 Use an antistatic bracelet or touch a grounded object regularly.
• 🔥 Do not overheat the fee with a hair dryer - maximum temperature is 80°C.

FAQ: Frequent questions about the proximity sensor on Xiaomi