Xiaomi Redmi 8 Pro is a popular smartphone with a good hardware stuffing, but even it is not immune to problems with sensors. One of the most common failures is the incorrect operation of the proximity sensor, which does not go out during the call, accidentally press the buttons with the cheek or, conversely, the display turns off for no reason. If you notice such symptoms, do not rush to carry the phone to the service: in 80% of cases, the problem can be diagnosed by yourself in 10 minutes.
In this article, we'll look at 5 working ways to test the proximity sensor on the Redmi 8 Pro, from hidden service codes to specialized applications, how to interpret test results, what are the normal values for this model, and what to do if the sensor is really faulty, and also reveal one little-known nuance about the effect of the protective glass on the operation of the sensor, which is not even in official instructions.
What is the proximity sensor and how it works in the Redmi 8 Pro
The proximity sensor is an optical sensor that detects the distance between a smartphone screen and an object (like your ear while you’re talking). The Xiaomi Redmi 8 Pro uses an infrared sensor consisting of two elements:
- 🔦 The emitter sends an invisible IR ray;
- 👁️ Receiver – captures the reflected signal and measures the time of its return.
When you hold the phone to your ear, the beam bounces off the surface and returns to the receiver, and the microcontroller analyzes the delay, and if it's less than 3 to 5 cm, turns off the screen and touchscreen, which prevents accidental taps during the call, and saves battery power.
On the Redmi 8 Pro, the sensor is located at the top of the screen, next to the front camera (see photo below).
- 📱 Glass purity – dirt or scratches can block the IR ray;
- 🛠️ Integrity of the plume - after falls or disassembly, the contacts can oxidize;
- 🤖 Software settings - failures in firmware or calibration.
Signs of malfunction of the proximity sensor
Before you test the sensor, make sure the problem is really related to it. Here are 5 key symptoms that indicate a proximity sensor failure in the Redmi 8 Pro:
| Symptoms. | Possible cause | Method of verification |
|---|---|---|
| The screen doesn't go out when you ring. | Sensor not detects approximation, glass contamination | Testing with ##6484## |
| The screen goes out arbitrarily | False positives, calibration failure | Checking in the engineering menu |
| Touchscreen is blocked for no reason | Problems with the plume or firmware | Diagnosis through MIUI Test |
| During the conversation, buttons are pressed. | The sensor does not disable touch input. | Hand-test with the palm |
Note that if the screen does not respond to touch at all (not only during the call), the problem is more likely to be the touchscreen or the display plume, rather than the proximity sensor, in which case a comprehensive diagnosis is required.
⚠️ Attention: On the Redmi 8 Pro, the proximity sensor is combined with the light sensor. If you have automatic brightness control at the same time, this may indicate a hardware failure of the module.
Method 1: Checking with service code ##6484##
The fastest way to diagnose is to use a hidden service menu, which is available on all Xiaomi smartphones and does not require the installation of additional applications.
Instructions:
- Open the Phone app.
- Enter the combination: ##6484### (some firmware may require ##64663###).
- Select Proximity Sensor (Proximity Sensor).
- Cover the top of the screen with your palm or finger.
Test results:
- ✅ Green screen + 0 - the sensor is operating correctly (responds to the approach).
- ❌ Red screen + 5 - the sensor does not work (calibration or replacement is required).
- ⚠️ The value jumps between 0 and 5 – false positives, glass contamination or software failure is possible.
Make sure the sensor is not directly illuminated |Rub the top of the screen with an alcohol wipe |Repeat the test after you reboot your phone |Check for MIUI-->
If the test shows a value of "5" with the covered sensor, try calibrating the sensor through the engineering menu (see Method 3).
Method 2: Manual check with the palm of the hand
This method requires no tools and helps to identify gross malfunctions, suitable if you do not have access to service codes or they do not work.
How to check:
- Call another phone or activate hands-free mode.
- Hold the Redmi 8 Pro to your ear, as you would during a normal conversation.
- The screen should go out instantly (within 0.5-1 seconds).
- Take the phone away from your ear, the screen should turn on immediately.
What is the norm for the Redmi 8 Pro:
- ⏱️ Reaction time: 0.3–0.8 seconds.
- 🔄 Repeatability: the screen is turned off/on with each lift.
- 🌓 Brightness: After switching on, it returns to the previous level.
⚠️ Warning: If the screen goes out only when you press the lock button or after 5-10 seconds, this is a sign of a software failure. Try resetting to factory settings (see Method 5).
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Before the test, turn off the function "Raise for activation" in the screen settings - it can interfere with correct diagnosis.
Method 3: Diagnostics through Engineering Menu (MTK Engineer Mode)
To test the proximity sensor in depth on the Redmi 8 Pro, you can use an engineering menu, which is suitable for advanced users and allows you to see raw sensor data.
Steps:
- Install the MTK Engineer Mode app from Google Play (if your Redmi 8 Pro is on a MediaTek processor). For Snapdragon, use Qualcomm Engineer Mode.
- Open the app and go to Hardware Testing → Sensors → Proximity Sensor.
- Pay attention to the parameters: Value - the current value (should change when the sensor is covered); Max Range - the maximum detection distance (for Redmi 8 Pro, the norm is 5-8 cm); Resolution - sensor resolution (should be 1 bit).
Cover the sensor and see how the values change.
Interpretation of results:
| Parameter | Normal value. | Sign of malfunction |
|---|---|---|
| Value | 0 (under cover) / 5 (in normal condition) | Constantly 5 or jumping chaoticly |
| Max Range | 5-8 cm | Less than 3 cm or more than 10 cm |
| Delay | 100-300 ms. | More than 500 ms. |
If the parameters are outside the normal range, try resetting the sensor calibration:
- In the engineering menu, find Proximity Sensor Calibration.
- Press Calibrate and wait for the process to be completed.
- Reboot the phone.
Instructions for Sensor Test:
- Download and install the app from Google Play.
- Start the Proximity Sensor test.
- Cover the top of the screen with your hand. If you work correctly, the indicator will turn green; Covered will appear; the value will change from Far to Near.
If the app shows an error or the sensor doesn’t respond, try:
- 🔄 Reboot the phone;
- 🧹 Clear the app cache Settings → Annexes → Sensor Test → Warehouse → Clear the cache;
- 📲 Check the sensor in safe mode (may be interfered with by third-party software).
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If all applications show the same error, the problem is almost certainly hardware (a sensor or plume is damaged).
Method 5: Resetting settings and updating firmware
If the proximity sensor was working normally but suddenly started to fail, the cause may lie in the software. On the Redmi 8 Pro, such problems often occur after:
- 📥 Updates MIUI (especially beta);
- 🔧 Custom firmware installations;
- 🧩 Conflict with applications (for example, launchers or optimizers).
What to do:
- Update your firmware: Go to Settings → About Phone → System Update; Download and install the latest version of MIUI; After the update, check the sensor through the service code.
- Reset to factory settings: Save important data (reset will remove everything from your phone!); Go to Settings → Additional → Reset and Reset → Reset settings; Choose to Erase all data and wait for completion.
Check in safe mode:
- Press the power button → Safe mode;
- Test the sensor – if it works, the problem is in third-party software.