How to check the proximity sensor on Xiaomi Redmi 8: diagnostics and repair

The proximity sensor in the Xiaomi Redmi 8 is a small but critical component that is responsible for turning off the screen during a phone call. When you bring the device to your ear, the sensor registers the obstacle and extinguishes the backlight, preventing accidental pressing and saving battery power. If this sensor fails, the phone becomes a real headache: the screen does not go out when you call, accidentally press buttons, and sometimes completely stops responding to touch.

The proximity sensor problems on Redmi 8 are more common than you might think, and software failures after MIUI updates, physical damage (for example, after a fall or moisture), and even trivial sensor contamination. In this article, we will discuss 5 reliable ways to check the sensor, from simple tests to diagnostics using an engineering menu, you will learn how to detect a malfunction without special equipment, what applications will help in the diagnosis, and what to do if the sensor really breaks.

Important: Before you sin on a hardware breakdown, make sure that the problem is not in the protective film or the case. Sometimes even a thin glass can block the signal of the infrared sensor. Try to remove all the accessories and repeat the test - perhaps you will not need repairs.

Signs of malfunction of the proximity sensor

How do you know if your Xiaomi Redmi 8’s proximity sensor isn’t working properly?

📱 The screen doesn't go out when you're calling, when you hold your phone to your ear, which is the most obvious thing. You have to manually lock the power button.
🔄 Spontaneous on/off screen in conversation: it goes out, then lights up again for no apparent reason.
📵 Gestures do not work (for example, putting your hand up to wake up the screen if they have been tuned).
🔋 Fast battery discharge – if the sensor is constantly active, it wastes additional energy.
🛠️ Artifacts on the screen when approaching the hand: flickering, color distortion or "ripples" at the top of the display (where the sensor is located).

Note that some of these symptoms may indicate other problems, such as a malfunction of the display module or a malfunction in the firmware, and to accurately diagnose the proximity sensor, you need to run several tests.

⚠️ Attention! If the Redmi 8 screen doesn't go out only in certain apps (like WhatsApp or Telegram), the problem is probably with the settings of those programs, not the sensor.

The most reliable way to diagnose is to use a hidden engineering menu, which is available on all Xiaomi smartphones, including the Redmi 8, and allows you to test the sensors without third-party applications.

Open the Phone app.
Enter the combination: ##6484### (some firmware may require ##4636##, then select Hardware testing).
You'll be taken to the Hardware Test menu. Find the Proximity Sensor section.
Put your hand up to the top of the screen (where the hearing speaker is located), and the numbers 0 (if the hand is close) and 1 (if the hand is removed) should appear on the screen.

If the values do not change or if the Failed error is displayed, the sensor is defective. Also note the reaction time: a delay of more than 1 second is considered abnormal.

Try to enter a code without characters * (just 6484)

Reboot the phone and re-enter

Update MIUI to the latest version

Use the alternative code ##4636##

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On some custom firmware, the engineering menu may be blocked, in which case move on to the next method.

Method 2: Application Testing (CPU-Z)

If standard methods don't work, third-party tools will come to the rescue, not only showing the status of the proximity sensor, but also providing additional information about other sensors, and we recommend two proven applications:

📊 CPU-Z — It shows the specifications of the device, including sensor data. After installation, go to the Sensors tab and find Proximity.
🔍 Sensor Test (from Innovative Apps) is a specialized tool for checking all sensors. The interface is intuitive: a green indicator means that the sensor is working, red indicates that the sensor malfunctions.

How to run the test:

Install one of the apps from Google Play.
Run it and find the section with the sensors.
Put your hand to the top of the Redmi 8 (where the speaker is).
Normally, the value should change from 5.0 cm (or similar) to 0.0 cm when approaching.

If the app shows that the sensor is not available, it can mean:

🔌 Sensor is physically disabled (check the plume after disassembly).
📱 The firmware does not support the sensor (relevant for custom). ROM).
🛠️ Hardware failure (requires a replacement module).

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Before installing sensor testing applications, turn off battery optimization for them in MIUI settings. This will prevent the utilities from automatically closing in the background.

Method 3: Visual inspection and cleaning of the sensor

Sometimes the problem isn't the electronics, it's the clutter, and the proximity sensor on the Xiaomi Redmi 8 is located to the right of the auditory speaker (if you look at the screen) and it's a small circular hole, and over time, it can get dust, sweat, or remnants of protective film, which blocks the signal.

How to clean the sensor:

Turn off the phone.
Take a toothpick (not a metal one!) or a soft brush (for example, for a camera lens).
Carefully, without pressing, clean the sensor hole. Don't use alcohol or liquids - they can damage the coating.
Blow the hole with compressed air (for example, a canister to clean the keyboard).

After cleaning, check the sensor in any of the ways described above. If the problem persists, proceed to the next step.

⚠️ Do not use cotton cotton swabs or cotton swabs to clean the hole, as the fibers can remain inside the hole and make the problem worse, and avoid sharp objects (needles, pins) to avoid damaging the sensor.

Method 4: Checking after the MIUI Update

Often, the proximity sensor stops working after a firmware update, and this is due to bugs in newer versions of MIUI, especially if you're using beta or custom builds.

🔄 Reverse to the previous version MIUI, If the problem appeared after the update. To do this, download stable firmware from the official Xiaomi website and run it through Recovery.
📲 Reset the settings to factory (remember to backup!) Sometimes it helps to get the sensor back up. → The phone. → Resetting settings.
🔧 Clear the cache of the system. To do this, press Volume up. + Power when your phone is turned off, then select Wipe Cache.

If the sensor is running after a firmware rollback, report the bug on the official Xiaomi forum or in the MIUI support group. Often such problems are fixed in the next updates.

MIUI version	Famous sensor bugs	Decision
MIUI 12.0.3	Sensor not responding to approach	Recoil on MIUI 12.0.2 or clear the cache
MIUI 12.5.1	False positives (screen goes out for no reason)	Update to MIUI 12.5.3
MIUI 13 (beta)	The sensor is running with a delay of 2-3 seconds	Disabling animations in the developer settings

Method 5: Hardware diagnostics (disassembly of the phone)

If the software doesn't work, it's just hardware testing, which is an extreme case, because you're going to have to take out the Redmi 8 and check the integrity of the sensor plume.

Turn off the phone and remove it. SIM-map.
With a plastic blade, gently pull the back cover (start at the bottom edge where the charging connector is). Be careful - the lid is attached to the latches!
Unscrew the screws that hold the metal plate over the battery.
Disconnect the plume that runs from the top of the screen to the motherboard, and that's where the proximity sensor is.
Check the plume for damage (breaks, oxidation) and clean the contacts with alcohol if necessary.

If the plume is intact, but the sensor is not working, the sensor itself is likely to have failed, in which case it will need to be replaced. The cost of a new sensor for the Redmi 8 is about 300-500 rubles, but note that the work on replacing the service center can cost 1-2 thousand rubles.

⚠️ Attention! Disassembling your phone leaves you with no warranty (if it's still valid), and there's a risk of damaging the display plume or other components. If you're not sure about your abilities, contact the service center.

What if the sensor doesn’t work after the disassembly?

If the proximity sensor did not work after cleaning the plume and checking the contacts, the reasons may be as follows: 1. The motherboard malfunction is damaged tracks or the sensor controller. 2. Problems with the firmware at a low level (for example, the partition with calibration data is damaged). 3. Mechanical damage to the sensor - in this case only replacement will help. Specialized equipment will be required for accurate diagnosis (for example, a multimeter to check the voltage at the sensor contacts).

Frequent errors in the proximity sensor

Many users make the same mistakes when trying to diagnose the sensor on Redmi 8.

🔨 Strengthen when disassembled -- the Redmi 8 back cover is mounted on the latches, and it can be broken if you pull too hard. Use plastic mediators.
💦 Water the sensor with alcohol or water – the liquid can get under the sensor and cause corrosion of contacts.
⚡ Use metal objects for cleaning – they can close contacts or scratch the sensor.
📴 Ignore updates MIUI — Sometimes sensor bugs are fixed in new firmware versions.
🔄 Resetting settings without backup – this can cause data loss if the problem is not with the sensor.

Another common mistake is to confuse the proximity sensor with the light sensor, which is responsible for automatically adjusting the brightness of the screen and is located nearby, but is tested differently (for example, through changing the lighting).

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If the proximity sensor stopped working after the phone fell or moisture hit, there's a 90 percent chance that it's hardware, and software won't help, it'll require disassembly and diagnostics.

FAQ: Answers to Frequent Questions

Can I calibrate the proximity sensor on Redmi 8 by myself?

Yes, but only if the problem is software. To do this: Enter the code ##6484## in the phone app. Select Proximity Sensor. Press Calibrate (if there is one). If there is no calibration point, the sensor does not support software configuration.

How much does it cost to replace the proximity sensor in the service center?

Cost depends on the region and service: 🔧 Official Xiaomi service: 1,500-2,500 rubles (with spare parts). 🛠️ Unofficial workshops: 800-1 500 rubles. the price may increase if you need to replace the plume or additional work.

Can the protective glass interfere with the sensor?

Yes, especially if the glass: 🔲 Too thick (more than 0.3 mm). 🖼️ It is not properly pasted (goes to the sensor area). 🛡️ It has a metallized layer (e.g., armored glass) and try to temporarily remove the glass and check the sensor.

What if the sensor is working but with a delay?

A delay of more than 1 second is considered abnormal. Try: Turn off animations in Developer Settings (path: Settings → About Phone → MIUI version – press 7 times, then return to Additional Settings → For Developers → Animation) Update the firmware to the latest stable version. Reset to factory settings. If nothing helps, the problem is in the hardware (wear of the sensor or plume).

Where is the proximity sensor on Redmi 8?

The sensor is located at the top of the screen, to the right of the auditory speaker, and it can be visually recognized by the visual signature of the speaker: 🕳️ Small round hole (diameter) ~1.5 mm). 📱 Proximity's diagram (if you can take your phone apart) is not to be confused with a front camera or light sensor (they're on the left).