The proximity sensor issues on the Xiaomi Redmi Note 9 Pro are a common complaint users face: The screen may not go out during a conversation or, conversely, stop responding to touch when you bring the phone to your ear. This situation is not only annoying, but also leads to accidental cheek taps, reset calls or turn on speakerphone at the most inopportune moment.
In most cases, the hardware is good, and the problem lies in software failure, contamination or incorrect calibration data. MIUI provides built-in diagnostic tools, and also hides the engineering menu available to advanced users. Understanding the way this sensor works will help you quickly fix the problem without going to the service center.
In this article, we will go through all the steps in detail, from simple cleaning to deep calibration through engineering code, you will learn how to properly prepare the device, what commands to enter and how to interpret the test results. Accurate adjustment will take no more than 10-15 minutes, but will return the comfort of using your gadget.
The principle of operation and causes of sensor failures
The proximity sensor in the Redmi Note 9 Pro is an infrared module located at the top of the screen, usually next to a conversational speaker. It emits invisible light and analyzes its reflection from objects. If an object (your ear or cheek) is less than 2-3 centimeters away, the system receives a signal and turns off the touchscreen to avoid false positives.
But this mechanism is often disrupted by external factors, and the most common, but common, reason is a protective glass or a film of poor quality, and if the accessory has a black frame or just too thick adhesive at the top, it blocks the sensor, and the work is also affected by the banal dirt, greasy spots or dust accumulated in the grid speaker.
Software causes include conflicts after a MIUI update or system processes that run on phone calls. Sometimes third-party applications that access the microphone and sensors can block the sensor from working properly. It is important to note that calibration is necessary precisely when the software values of "distance" are lost and the phone no longer knows where the object is.
⚠️ Note: If the top of the screen was replaced or disassembled, the sensor may have been displaced or damaged by the plume.
Basic preparation and cleaning of the device
Before you go to complex engineering manipulations, you need to eliminate physical interference. Owners of the Xiaomi Redmi Note 9 Pro should carefully examine the top bezel of the display. Even a microscopic speck of dust in the sensor hole can distort the readings.
Take a soft microfiber cloth and gently wipe the top of the screen. If you have a protective glass installed, try gently wipe the area above the speaker. In some cases, removing the case, which can hang over the edges of the display and block the view of the sensor, helps.
After physical cleaning, it is recommended to program reset the sensor settings through the standard menu, which will not delete your personal data, but will update the system configuration files.
- 🧹 Carefully wipe the area of the speaker with an alcohol napkin.
- 📱 Remove the protective glass if it has a darkened frame or thick edges.
- 🔄 Reboot your smartphone to reset temporary driver errors.
- 📞 Check the work in the "Safe mode" to exclude the influence of third-party applications.
The MIUI firmware on the Redmi Note 9 Pro has a hidden hardware testing section known as the CIT (Customer Integration Test), the most reliable way to check if the phone sees the presence of a sensor at all and what data it transmits.
To enter the diagnostic menu, you do not need to install additional software. Just open the standard phone application and enter a special one. USSD-Once you enter the last digit, the menu will automatically open.
##6484##
When you open the test list, look for the Proximity sensor. Click on it. You'll see a screen with numerical values and two buttons: usually "Pass" and "Fail" or "Calibration." Hold your palm to the top of the screen and remove it. If the values change (e.g., from 5.0 to 0.0 or vice versa), then the sensor is physically healthy.
What do the numbers in the CIT test mean?
The numerical values in the test indicate the distance in centimeters or the conventional units of illumination. If the value does not change when you put your hand and remains constant (for example, always 5.0), this indicates a software unit or a physical malfunction of the sensor. If the value "jumps" by itself without the touch of the hand - it is possible contamination or interference from the screen."> Manual calibration of the sensor if the test CIT The sensor has shown that the sensor is responding but is not working correctly (e.g., it is turning off the screen too soon or too late), and it needs to be calibrated. CIT You often have a Calibration button. You click on it and follow the instructions on the screen. The system will ask you to remove your hand from the screen and then close the sensor. In some versions MIUI on the Redmi Note 9 The pro process looks like this: you press "Start", remove all objects from the screen, wait. 3-5 You close the top of the top with your palm, and when you're successful, you'll see "Pass" or "Success." Sometimes, one attempt is not enough. If you don't calibrate the first time, repeat the procedure. 2-3 Also make sure you're not in bright sunlight, which can blind the infrared sensor and knock your settings off. 🖐️ Remove all objects at a minimum distance 30 cc from the screen before the start. ⏱️ Hold the pause in 3-5 Seconds between actions, as the system asks. ☀️ Avoid direct sunlight on the sensor area during setup. Configure through the engineering menu MTK If the standard menu CIT does not give results or the calibration button is absent, you can use the deep engineering menu of the MediaTek platform (MTK), This is a more powerful method, but it requires caution, and it also uses the code in the Phone app to access this menu, and you enter the code and you open up a list of engineering tests. You need to find a partition associated with the sensor, often called Hardware Testing -> Sensor -> PS (Proximity Sensor. #3646633## Inside the menu PS Select the tab "Sensor Calibration." There's a button called "Do Calibration." Press it and do the same thing: remove your hand, then close the sensor. Once you're done, click "Get Calibration Data" to make sure the data is recorded (Min and Max will appear). At the end, be sure to press Set or Save to save the changes to your memory. ⚠️ Attention: In the engineering menu MTK Do not change other parameters if you are not sure of their purpose, this can lead to unstable operation of the communication or other modules of the phone, reset and update software Sometimes the problem lies not in the sensor itself, but in the error of the system application "Phone" or the shell. MIUI. In this case, it helps to clean the app cache or completely reset settings. Go to Settings → Annexes → All apps, find Phone and Google Play Services, then select Clear Cache and Clear Data. Check for system updates. Xiaomi regularly releases patches that fix sensor drivers. Go to Settings → The phone. → Version. MIUI and press the update check button. If a new version is available, install it. In extreme cases, if nothing works, you can do a full factory reset, and it's important that you back up all the important data before you do that, because it's going to be deleted. Method of solution Efficiency Data loss risk Difficulty Screen cleaning High (when polluted) No Low Calibration in CIT Medium/High No Low Engineering Menu MTK High No Average Resetting High (with software bugs) Yes (full) High 📊 Did you manage to solve the sensor problem? Yes, simple cleaning / Yes, calibration in the CIT/Yeah, through the engineering menu. MTK/No, I needed repairs Frequently Asked Questions (FAQ) Why does the proximity sensor not work after changing the screen? 9 Pro often use unoriginal parts or poorly glue sealing gum. This causes the light from the backlight to hit the sensor directly, blinding it. Could the plume be damaged when the MIUI is not installed properly. Can a virus block the sensor? In theory, malware can intercept the sensor's control, but in practice this is extremely rare. Most often, the "optimizers" of the battery or applications for recording calls that constantly poll the sensor and cause conflicts. Is the calibration reset after the MIUI update? Yes, major system upgrades (for example, switching from UI 12 to 13) can reset the calibration of the MIIT in the CIT item, if it is strange to do the CIT updates after the CIT's. Try re-entering the code ##6484## or using the alternative code ##3646633## to access the full engineering menu.