Xiaomi's Redmi series is famous for its functionality, but sometimes users find that the screen does not go out during a phone conversation. This creates inconvenience: you can accidentally hit the off button or activate the speakerphone with your cheek. On the Redmi 9T model, a special sensor is responsible for this function, which often requires proper adjustment or calibration.
In the MIUI operating system you have installed on your device, the locking mechanism is tied to the proximity sensor, and if it doesn't work properly, the screen continues to glow even when you hold the phone to your ear, and there are several proven ways to address this problem, from simple menu settings to engineered sensor calibration.
In this article, we will discuss how to make the screen go out during a conversation, we will look at standard settings, how to clean the sensor cache and how to force the sensor to turn on if it was turned off programmatically, carefully following all the steps will help restore comfort when communicating.
The approach sensor on the Redmi 9T
The automatic screen-crushing is done by an infrared proximity sensor, which is located at the top of the smartphone, usually next to the speaker, and during the call, this sensor constantly scans the space in front of the screen, and as soon as the distance to the object (your ear) is below a certain threshold, the system receives a signal and turns off the display.
On the Redmi 9T, the sensor can be both physical and virtual, depending on data processing algorithms. If there is a poor-quality protective glass, dirt or greasy traces in the path of the sensor, the signal can be distorted, as a result of which the phone "thinks" that it is lying on the table, and does not lock the screen.
It's important to understand that the MIUI software shell can sometimes fail when processing signals from hardware modules. It doesn't mean that the phone is broken, it just indicates that a software adjustment is needed. Calibration helps the system redefinite zero values and trigger thresholds.
⚠️ Warning: If you use a wide black bezel or cutout, it may overlap the sensor. Make sure the area above the speaker is clean and not closed.
Sometimes the problem is that the sensor function is simply disabled in hidden settings or lost after updating the firmware, so the first step should always be to check the basic parameters of the system.
Checking the basic settings of the phone
Before you go to the complex steps, you need to make sure that the standard interface is not a restriction that prohibits blocking.In some versions of MIUI, settings can be reset or changed by third-party applications.
You have to open the standard Phone app that you use to dial a number. Click on the three dots in the top right corner or the gear icon to get into the call settings menu. Find the section associated with incoming calls or the screen while you're talking.
- 📱 Make sure the proximity sensor switch is active and lit in blue.
- 🔔 Check if Pocket Mode is enabled, which may conflict with the sensor.
- 📞 Make sure that the theme does not cover the system controls of the call.
If this menu is all on, but the screen is still not going out, the problem can be deeper, sometimes it helps to just restart the telephony service, and you can just restart the smartphone by pressing the power button and selecting the appropriate item.
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Before setting up, be sure to wipe the top of the screen with a soft cloth. Even a discreet film of fat can block the sensor's infrared radiation.
Calibration of the sensor through the engineering menu
The most effective way to make the screen go out correctly is to calibrate. There is a special engineering menu available through code on Xiaomi and Redmi smartphones, a safe procedure that does not require superuser rights (Root).
Open the Phone app and dial ##6484##. The CIT menu should appear on the screen. If the menu doesn't open, your firmware version may be blocking the code, and then you'll have to look for alternative ways.
In the test list, look for the Proximity Sensor. Click on it. You'll see the current sensor readings. Hold your palm to the top of the screen and remove it. Value should change from 5.0 to 0.0 (or vice versa, depending on the version). If the numbers don't change, the sensor doesn't see any obstacles.
To start calibration, press Calibration or Pass (if the system suggests it). Follow the instructions on the screen: it is usually necessary to close the sensor several times with your hand and then open it. Once the test is completed successfully, press Back and save the changes if necessary.
☑️ Sensor calibration
Resetting the phone application
Sometimes a software failure accumulates in the cache of the system application that handles the calls, in which case even a properly functioning sensor will not work properly due to a bug in the logic of the software, the solution is a complete reset of the application data.
Go to Settings → Applications → All apps. Find the Phone app (green handset icon) in the list. Click on it and select Memory. Here you click Clear and select All Data.
Don't worry, your contacts and call history won't be deleted because they're stored in a separate database or synced to your Google account, and the reset only affects the settings of the call app itself, and after that, the phone may be a little slower when you first start dialing, but then everything will recover.
| Action. | The result | Risk of data loss |
|---|---|---|
| Clearing the cache | Deletion of temporary files | No. |
| Clearing all data | Resetting the call settings | No (contacts are safe) |
| Deletion of the annex | Impossible (systemic) | High-pitched |
| Resetting phone settings | Fully back to factory | Yes (all data) |
What to do if the “Clean” button is inactive?
Use of additional applications
If the built-in Redmi 9T tools failed to solve the problem, you can resort to the help of third-party software. In the Google Play store, there are utilities that forcibly control the proximity sensor, ignoring system errors.
One popular solution is the Proximity Sensor Reset & Test app, which allows you to perform deep calibration that is not available in the standard menu, and there are also callers with their own sensor processing engine, such as Truecaller or Google Phone.
- 📲 Install a calibration application from a reliable source.
- 🔧 Start testing and follow the instructions on the screen.
- ✅ Restart the device after the procedure is completed.
It’s worth noting that installing third-party calling apps can change the dialing interface. However, if the standard screen lock feature doesn’t work, it becomes the lesser of the evils. Many users note that switching to Google Phone completely solves the sensor problem on older versions of MIUI.
Hardware causes and physical damage
And you can't rule out a physical breakdown, and if software methods, calibration and data resetting didn't work, maybe the proximity sensor went down, which is often the case when a smartphone falls down or when moisture gets inside the case.
In the Redmi 9T, the sensor can be combined with a front camera module or a speaker, and when changing the screen or glass, unscrupulous wizards can damage the plume or not connect the connector properly, and oxidation of contacts over time leads to loss of signal.
If the sensor is always 0.0 or 5.0 and does not respond to hand-holding even after calibration, repair is likely required.
⚠️ Warning: Don't try to disassemble the phone yourself if you don't have experience. The proximity sensor is very fragile and easily damaged if you sloppy open the body.
If you have a physical malfunction, you can only go to an authorized service center, and replacing the sensor is a very inexpensive and quick procedure, and sometimes just cleaning the plume contacts with a special solution is enough.
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If the sensor does not respond in the engineering menu even after calibration, the problem is hardware in nature and requires the intervention of the wizard.