Location of the proximity sensor on Xiaomi Redmi: search and diagnosis

Xiaomi and Redmi smartphone owners often face a situation where the screen goes out during a conversation, but the interlocutor is not heard, or, on the contrary, the screen is on fire and the buttons are accidentally pressed with the cheek. All this is due to the operation of the sensor that determines the distance to the face. Understanding where the proximity sensor on Xiaomi Redmi is located is key to solving these problems. In modern models, this element can be hidden under the display or displayed in a narrow frame.

Knowing the exact location of this component is essential not only for the proper installation of the protective glass, but also for manual calibration. Proximity Sensor malfunction can cause serious discomfort when using the device on a daily basis. In this article, we will discuss in detail the physical features of the location of the sensor in different series of phones.

There are two main types of design that determine the location of the sensor: budget and old models use a classic circuit with a separate window; more expensive and new devices use in-display technology, where the sensor is hidden; differences in design dictate different approaches to diagnostics of malfunctions.

Physical location in different Redmi series

The sensor search begins with a visual inspection of the top of the front panel. In classic models like the Redmi Note 8 or Redmi 9A, there's a prominent black bar above the screen. It's in this area, often to the right of the speaker, that the infrared emitter and receiver are located, and it looks like a small round or oval window that's not part of the display matrix.

In models with a cutout in the screen, like the Redmi Note 9 Pro or Redmi Note 10, that's changing, where the sensor is often hidden in the upper end of the case, directly above the screen, a narrow slit that you can only see if you look closely in bright light, which allows you to increase the usable area of the screen, but makes the sensor more vulnerable to contamination.

Flagship models and mid-range devices with a hole in the matrix (punch-hole), such as the Redmi Note 11 or Redmi K40, use hidden sensors. They do not have a visible window above the screen. The light-sensitive element and the emitter are under the display glass. This creates additional requirements for the quality of protective films — they should not overlap the area of operation of the sensor, even if it is not visible to the eye.

It is important to consider that in some rare cases, especially in tablets or devices with a rotary camera, the logic of the location may differ. However, for the bulk of Xiaomi smartphones, the rule of "top third of the case" remains unchanged. If you can not find the sensor visually, refer to the specification of your model on the official website.

⚠️ Warning: Do not attempt to pierce or mechanically impact the sensor area with sharp objects in an attempt to clean it from the inside, and this is guaranteed to damage the plume or the matrix itself.

Types of sensors and their visual differences

Understanding the type of sensor you have installed helps you determine the cause of the failure faster. Infrared sensors that have a visible window work on the principle of beam reflection. They are less dependent on the brightness of external light, but require line of sight. If there is a chip or a greasy spot on the security glass in this place, the phone will think that it is in the pocket.

Optical sensors that work through the screen use pixel brightness and reflection analysis of reflected light. They are more sensitive to the quality of protective coatings. Cheap hydrogel films or thick glass with a black frame can completely block the operation of such a sensor, visually distinguishing them only by the absence of a separate hole on the front panel.

There is also an ultrasonic operating principle that is less common, mostly in more expensive lines, which are sometimes released under the Xiaomi brand, rather than Redmi.Such systems are practically unaffected by contamination, but can fail when using certain types of covers that overlap the bottom or top edge.

When choosing accessories, always pay attention to compatibility with the type of sensor you have. Security glass manufacturers often say "accommodation sensor compatible," but in practice this means that there is no black bezels in the desired area.

Software diagnostics and testing

Before you bring your phone to the service, you need to make sure that the problem is hardware or contamination, not software failure. The MIUI and HyperOS shells have a built-in engineering menu to check all the components, and access it through a standard dialer.

To run the test, open the Phone app and dial ##6484##. This will open the CIT menu. You'll find the "Proximity Sensor" or "Proximity Sensor" item in the list, and you'll click on it and you'll enter the testing mode, where the screen will change color when you put your hand up.

• 📱 Hold your hand to the top of the screen for a distance. 2-3 centimeter.
• 👁️ Remove your hand and make sure the indicator on the screen reacts (changes from Near to Far).
• 🔄 Repeat the procedure several times to rule out accidental positives.
• 🧹 Wipe the top frame with an alcohol napkin if the reaction is delayed.

If the engineering menu is successful, but the screen goes out on its own in life, the problem may be in third-party applications. Often flashlights or memory cleaner applications request access to the sensor and block it from working. Check the list of recently installed programs.

Calibration of the sensor in the system settings

Often times, the sensor is physically functional but the sensor is downed, and this requires software calibration, which can be done without rooting on Xiaomi phones, using the hidden menu of engineering tests that we talked about earlier, or through development settings.

After entering the CIT test and selecting "Proximity Sensor", press the "Calibration" button, you will be asked to close the sensor with your hand (or put the phone on a flat surface, covering the top), and then remove the obstacle, the system will record minimum and maximum light values.

An alternative is available through the Developer Menu. To activate it, you need to quickly click 7 times on the build number in the About Phone section. Then, in the advanced settings, find the item associated with the sensor. However, in newer versions of Android, direct calibration is often removed from there, and the method through CIT remains the main one.

⚠️ Note: If the test fails after calibration in the engineering menu (burns red), it indicates a physical malfunction of the component or from the plume.

Problems with protective glass and films

One of the most common causes of failure is to replace the protective coating. Users buy cheap glass with a black edging that covers the working area of the sensor. Even if the glass is transparent, but has a thick layer of glue or low transmittance, the optical sensor can "blind".

This is especially true for models with hidden sensors, where only replacing the accessory with an original or certified one (marked "Full Coverage compatible" or "Case Friendly") helps, sometimes temporarily removing the glass to test the hypothesis.

If you glue the glass yourself, make sure it's glued evenly. A half-millimeter shift can cause the edge of the black frame to overlap part of the sensor. For models with a sensor in the end (Redmi Note 9 Pro), it's important that the glass doesn't have curved edges (2.5D/3D) that create shadow over the sensor slit.

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Use an ultraviolet lamp to check the protective glass. Under UV light, you can often see how tightly the glass fits in the sensor area and whether it creates optical distortion.

Impact of MIUI Updates and Third Party Software

It's no secret that after updating MIUI, users often complain about the strange behavior of the screen, because new versions of the operating system can interpret sensor data differently, and sensitivity thresholds sometimes get confused.

In such cases, resetting sensors through the engineering menu (recalibration) helps. If this does not help, you can try to clear the data of the system application Phone and Contacts. Go to Settings → Applications → All applications, find Phone and click Clear → All data.

It's also worth checking if you have a Theme with a changed lock or call screen, and some custom themes conflict with standard sensor drivers, and switch to the standard "Classic" or "Unnamed" theme to rule this out.

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90% of sensor problems are solved by correct calibration CIT-menu or replacement of poor quality protective glass.

Frequently Asked Questions (FAQ)