Modern smartphones like the Xiaomi Redmi 9T come with a variety of hidden modules to make the device comfortable to use. One of the most important elements is the sensor responsible for turning off the screen during a conversation. Users often wonder where exactly the proximity sensor on the Xiaomi Redmi 9T is, especially when faced with the fact that the screen does not go out when you bring the phone to your ear. This can lead to accidental cheek pressing and unwanted actions, such as turning on speakerphone or resetting a call.
Unlike older models, where the sensor could be placed as a separate black eye above the display, the Redmi 9T uses hidden placement technology to increase the usable screen area and improve the aesthetics of the device. Understanding the physical location of this component is necessary not only for theoretical knowledge, but also for proper diagnosis, cleaning or repair in the event of a module failure. In this article, we will discuss in detail the design features, methods of software verification and ways to solve typical problems.
Physical location of the sensor in the case of Redmi 9T
On the Xiaomi Redmi model 9T And the engineers have actually applied a circuitry to integrate the sensor directly under the top of the display, and visually you won't see a single hole or a black circle in the top frame, because you're using an infrared transmitter and receiver that's hidden behind the layer. OLED-matrix LCD-The module is physically located in the upper central part of the smartphone, directly above the display area of the image, often combined with a conversational speaker.
This arrangement is dictated by the need to read reflected infrared radiation from an object (your ear or cheek). The distance between the protective glass and the sensor itself is minimal, which ensures high sensitivity. However, this proximity makes the module vulnerable to contamination, dust and poor quality protective films that can block the signal. If you use a dense protective glass with a black frame, make sure that it does not cover the upper center of the screen.
Importantly, there may be modifications in some regions or versions of MIUI firmware that combine the sensor with the front camera, but the Redmi 9T features a classic top-central location, which is standard for the budget and mid-range segment, allowing you to reduce the cost of production without losing functionality. Knowing the exact location helps with hardware diagnostics when you need to open the case to replace the plume.
- 📍 The sensor is hidden under the upper end of the display, visually not visible.
- 🔊 Often constructively combined with the module of the conversational speaker.
- 🛡️ Sensitive to thickness and quality of protective glass and films.
- 📡 It works on the principle of infrared radiation and reflection.
Diagnostics of work through the engineering menu
To check the serviceability of the hardware-part without contacting the service center there is a built-in toolkit MIUI. The engineering menu allows you to test all the sensors, including the accelerometer, the gyroscope and, of course, the proximity sensor. USSD-This is the most reliable way to tell if the system sees the physical presence of the sensor.
Once you enter the code ##6484## (or #4636### in some versions), the CIT menu will open. You will need to find a item in the list that can be called "Proximity Sensor", "Proximity Sensor" or have an appropriate icon. When you enter this section, the screen will turn white or black, and the system will read the readings. You need to hold your palm to the top of the phone and remove it. If the values change (for example, from 5.0 to 0.0 or Near/Far), then the physical module is functional.
⚠️ Note: If the test does not start in the engineering menu or the values do not change when closing the top of the screen, the problem can be both software (driver failure) and hardware (from the plume or oxidation of contacts).
There is also an alternative method of checking through the developer's settings, but it is less informative for the average user. In the CIT engineering menu, a calibration function is often available, which can help if the sensor is lying for a split second. Don't ignore this step, since it takes less than a minute, but gives a clear understanding of the state of the equipment. If the test is successful, you should look for the problem in software conflicts or system settings.
☑️ Checking in the engineering menu
Software calibration and system settings
Even if the sensor is physically correct, software failures can lead to malfunction. Xiaomi smartphones often have a situation where after updating the firmware or falling calibration data is confused. To correct this, there is a hidden calibration menu. To get into it, you sometimes need to enter the code # #64663## or find the corresponding item in the same CIT engineering menu, which was mentioned above.
The calibration process is usually as follows: you cover the top of the screen (where the sensor is) with your finger, the system picks up the value "close", then you remove the finger, and the system picks up "far". After that, you press the "Pass" or "Save" button. It is critical to calibrate in bright, but not direct sunlight, because the infrared spectrum of the sun can distort the sensor readings. After successful calibration, the phone may require a reboot to apply new parameters.
It is also worth checking the basic system settings that can block the sensor. In some versions of MIUI, there is a “pocket mode” function or lock settings when calling. Go to Settings → Screen lock or Settings → Apps → Phone and make sure that access rights and sensor functions are not limited to energy saving. Disabling battery optimization for the “Phone” application often solves the problem of spontaneously turning on the screen.
| Parameter | Normal value. | Sign of malfunction | Action. |
|---|---|---|---|
| Status at CIT | Pass / OK | Fail/Mistake | Reboot or replacement |
| The value of Distance | Changes 0 ↔ 5 | A frozen number | Sizing |
| Screen reaction | Extinguish in 0.5 seconds | Delay > 2 seconds | Resetting settings |
| Indicator | Green/Blue | Red/Migaet | Driver verification |
Influence of accessories and protective glasses
One of the most common reasons why the proximity sensor on the Xiaomi Redmi 9T does not work is the wrong accessories. Protective glass with a wide black frame (so-called "full glue" or 3D/4D/5D glass) often block the IR sensor. Since the sensor is very close to the edge of the display, even a minimal displacement of glass by 1-2 millimeters can completely block the signal.
In addition, cheap hydrogel films or thick glasses may not have enough transparency for the infrared spectrum. Although the human eye sees through them the image, the infrared rays can be scattered or reflected inside the glue layer, creating a constant "approach" effect, as a result of which the phone thinks that it is in the ear all the time, and the screen either does not light up at all, or, on the contrary, does not go out due to noise.
To diagnose this problem, it is enough to temporarily remove the protective glass or film and test in the engineering menu. If without the accessory everything worked, the problem is solved. In this case, it is recommended to replace the accessory with a model with a cutout for the sensor (if the design of the case allows) or use glass with a smaller black frame area. Quality branded glasses usually take into account the location of the sensors of specific models.
Can I make a cut in the protective glass?
Hardware malfunctions and repair methods
If software methods and removal of protective glasses did not help, hardware failure is likely. In the Redmi 9T, the proximity sensor is often soldered on a separate plume coming from the main board, or integrated into the charging port plume (depending on the revision of the board), or is part of the display module. A frequent problem is the oxidation of connector contacts after moisture or just from time to time.
Repairs require partial disassembly of the device: removal of the back cover (it is glued, you need warming), battery disconnection and visual inspection of the plumes. If the sensor is placed on a separate plume at the top, it is inexpensive to replace it. However, if it is integrated into the display module, replacement may not be economically feasible, and users often get used to living with this feature or use software crutches.
⚠️ Attention: Independent disassembly Xiaomi Redmi 9T It requires skills and tools (dryer, suction cups, mediators) and a sloppy autopsy can damage the battery or rupture the plumes, leading to more expensive repairs.
It's also worth checking the state of the speaker itself, because in this model, they're often structurally connected. If the speaker wheezes or falls inside the housing, it can mechanically clamp or shift the sensor. In diagnostics service centers, they use a multimeter to vertebrate the sensor's power circuits. If there's voltage and there's no reaction, the module is dead and needs to be replaced.
💡
Use isopropyl alcohol to clean the top of the screen carefully (without removing the protective glass) to remove fat spots that can distort the sensor.
Software solutions and third-party applications
When (hardware) is working, but system bugs are troubling, third-party solutions come to the rescue. There are many calibration apps on the Google Play Store, such as "Proximity Sensor Reset/Fix" or "Sensor Test," which allow you to force the sensor driver to restart or conduct deep calibration that is not available on the standard menu.
Another effective method is to reset all phone settings to factory settings.This is a radical step that requires a data backup, but it often eliminates system file conflicts that have accumulated over the years of use. Before resetting, make sure that the problem is not with a specific call app (for example, if you use Viber or Telegram instead of a standard call).
For advanced users with Root rights, there is the option of editing system configuration files (build.prop or files in the /sys/ folder) where you can change the sensitivity of the sensor. However, for Redmi 9T with its current versions of Android and bootloader protection, this method is complex and risky.
Why does the screen go out in your pocket without a bell?
Can the proximity sensor be completely turned off?
Does the phone reboot affect the sensor?
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In 90% of cases, the problem is solved by removing the protective glass, cleaning the top of the screen or software calibration through the engineering menu.
To sum up, the Xiaomi Redmi 9T's proximity sensor is a robust, clean and customizable module. Its under-screen location dictates its own rules of operation: the use of quality accessories and periodic health checks. Understanding how it works will allow you to diagnose most malfunctions yourself without resorting to expensive repairs. Keep the top bezel clean, update the software and calibrate in a timely manner so that your smartphone serves you faithfully.