How to calibrate the proximity sensor on Xiaomi Mi Mix 2s: the complete guide

The Xiaomi Mi Mix 2s was a revolutionary device of its time, offering users the concept of a “screen without bezels” long before it became the mainstream industry standard. However, this bold design feature has led to a number of specific problems, one of which is the incorrect operation of the proximity sensor. Owners often face a situation when the screen does not go out during a conversation, or, conversely, goes out when the phone is a few centimeters from the face, making it impossible to use hands-free communication or control the call.

Compounding the problem, this model has a sensor at the bottom of the body, rather than above the display, as in classic smartphones. This makes it extremely sensitive to contamination, protective films, covers and even software failures of the MIUI system. If you notice that your device has stopped responding to the ear or, conversely, "blind" in the hands, urgent calibration is necessary. In this article, we will discuss all methods for restoring the sensor to the simple software solutions to complex manipulation of the engineering menu.

Before we take any drastic measures, we need to rule out the trivial physical causes of the malfunction. Often users are unaware that the problem lies in banal dust or an incorrect accessory. The proximity sensor in the Mi Mix 2s is an optical module that emits and receives infrared light, and any obstacle in its path distorts the readings.

Physical diagnosis and device preparation

The first step in fixing the problem is to carefully check the sensor area visually and tactilely. In the Xiaomi Mi Mix 2s, the sensor is located at the bottom of the front panel, right under the screen, in a narrow strip where the speaker is also located. If there is a crack, chipped or thick layer of dirt on this piece of glass, the system cannot work properly. The optical sensor requires line of sight, and even a microscopic layer of fat from the fingers can block infrared radiation.

Special attention should be paid to protective accessories. Many flagship owners prefer to protect expensive devices, but not all manufacturers of covers take into account the specifics of the lower location of the sensor in the Mi Mix 2s. If the side of the case comes to the bottom frame, it creates a permanent shadow, which the system perceives as the proximity of the object to the face, in which case calibration by software methods will be useless, since the physical obstacle will not go away.

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Use microfiber and isopropyl alcohol to clean the bottom of the screen, as conventional remedies can leave a greasy film blocking IR rays.

It's also worth checking if there's a black-framed glass that covers the work area, and some universal glasses have a darkened area from the bottom that hits the sensor, so the only solution is to replace the glass with a model specifically designed for the Xiaomi Mi Mix 2s, which takes into account the lower location of the sensors.

⚠️ Warning: If after removing the case and thoroughly cleaning the problem persists, do not try to disassemble the smartphone yourself if you do not have experience.

Standard calibration through CIT's engineering menu

The most effective and safe way to solve software errors is to use the built-in CIT (Component Integration Test) engineering menu, a tool created by Xiaomi engineers to diagnose all nodes of a smartphone and allow you to reset and recalibrate sensors without installing third-party software.

Once you type in ##6484## or #4636## (code can vary depending on the version of the MIUI firmware), the test list will automatically open on the screen. You need to find a item called "Proximity sensor" or "Proximity Sensor." By clicking on it, you will be taken to the testing window, where the current state of the sensor will be displayed: "Near" (close) or "Far" (far).

In the calibration process, you will be asked to close the sensor with your hand (or hold the phone to your face), and then remove the obstacle. The system should record both states. If the reading changes correctly, but there are malfunctions in real use, press the Calibration or Start button to force the reset. After successfully completing the test, which is confirmed by a green indicator or the inscription "Pass", you need to reboot the device.

It's important to understand that the engineering menu is a powerful tool, but it's not all-powerful for physical damage. If after a few attempts at calibration in the CIT menu, the test still fails, it's a sure sign that the problem lies deeper, perhaps in the hardware plume or the sensor module itself.

Using the Phone Sensor app to fine-tune

In some versions of MIUI firmware, the standard engineering menu may not work properly or be stripped down, and in such cases, the official or semi-official Phone Sensor (or Testing) app comes to the rescue, often pre-installed in the Service or Tools folder, which provides a more detailed interface for sensors and allows you to see numerical values, rather than just a near/far status.

When you start the app, select the "Proximity Sensor" tab, and you'll see a graph and numerical values in luxes or units of distance, and your goal is to make sure that when you move your phone away from objects, you hit the "Calibrate" button and follow the instructions on the screen. The process usually takes no more than 10-15 seconds.

The advantage of this method is that it allows you to calibrate the sensitivity of the sensor. If the screen goes out when the phone is 5 cm from the face, and not 1-2 cm as it should, then the threshold of response is knocked down. Phone Sensor app allows you to adjust this delta, making the smartphone more comfortable.

⚠️ Warning: Do not press the "Reset" button in the sensor menu unnecessarily unless you are confident in your actions.Reset can cause the sensor to stop responding at all and require flashing.

Solving problems through the Developer Menu

If standard methods fail, you can try activating hidden settings through the developer menu, which often helps when a problem is caused by a software conflict on the Android system or the MIUI shell itself. To log into the developer menu, you need to go to Settings → About Phone and quickly click on the MIUI version seven times.

After activating the menu, go to “Advanced Settings» → «For developers. You'll need to find a section that's associated with inputs or sensors. Look for "Quick start to proximity sensor" or something like that. Try to change the state: if it's on, turn it off, and vice versa.

Also on the developer menu, you should pay attention to the animation and energy saving settings. Sometimes aggressive energy saving turns off the proximity sensor to save charge, which leads to its malfunctioning. Turn off battery optimization for system processes responsible for phone calls.

It is worth noting that interfering with the developer's settings requires caution, changing parameters that are not associated with sensors can lead to unstable operation of the entire system, so after making changes to the Proximity Sensor operation, it is recommended to immediately check the result and, if successful, do not touch the rest of the parameters.

Third-party calibration and discharge applications

When Xiaomi’s built-in tools are powerless, users often turn to third-party software from the Google Play Market. Applications like Proximity Sensor Reset & Calibration or Sensor Test can have more advanced calibration algorithms than standard utilities, which work by forcing new base values to be written into the controller’s memory.

However, using third-party software on Android always carries certain risks: such applications require wide permissions, up to access to system settings. Before installing, make sure that the developer has a good reputation and the application is highly ranked. For the Mi Mix 2s, the Proximity Sensor Fix app has proven to be a good one, which automatically resets the calibration every time the screen is turned on.

The process of using these programs is usually simple: you run the application, put the phone on a flat surface, cover the sensor and wait for the process to be completed, and then the application can suggest restarting the device.

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Third-party applications are a last resort, and if they don't work, it's either a deep system failure that needs to be reset or a hardware problem.

Some apps also offer a “calibration while talking” feature, where the phone itself analyzes your actions and adjusts the sensitivity in real time.This can be useful if the standard calibration “does not catch” your smartphone usage habits.

Radical measures: resetting and reflashing

If none of the software methods worked, there may have been some critical errors or configuration file conflicts in the system, in which case the only software solution is a full Hard Reset, and make sure to back up all the important data before this procedure, as it will be permanently deleted.

To perform the reset, go to Settings → Advanced Settings → Recovery and Reset. Select Reset and confirm the action. Once the reset is complete, the phone will be as new and the proximity sensor should be recalibrated during the initial setup. If that doesn't work, then you just need to flash the device through your computer using the Mi Flash utility.

Flashing is a complex process that requires an unlocked bootloader. You will need to download the official firmware for the Mi Mix 2s from the MIUI bootloader site, install ADB drivers, and follow the instructions. Clean installation often eliminates software bugs that cannot be fixed by conventional means.

⚠️ Warning: Flashing a device with a locked bootloader can turn a smartphone into a “brick.” If you are not sure of your abilities, you better contact the service center.

It’s also worth mentioning that in rare cases, the problem is solved by updating the system to the latest available version. Xiaomi engineers regularly release patches that fix the driver.

Hardware causes and module repairs

When all software methods are exhausted and the proximity sensor on the Xiaomi Mi Mix 2s continues to work incorrectly, with a high degree of probability we are talking about a hardware malfunction, this can be a waste plume, oxidation of contacts (especially if the phone was in contact with moisture), or the physical failure of the sensor module itself.

In the Mi Mix 2s, the proximity sensor is often integrated into the bottom speaker plume or part of a separate μικ chromomodule glued to the frame. Over time, the glue dries up, the module shifts, and its axis goes wrong, requiring the removal of the smartphone, cleaning the contacts, and possibly replacing the plume or re-adhearsing the sensor.

Self-repair is possible only with the experience and tools: thermophene for opening the body, thin blades, microscope and soldering equipment. If you do not have these skills, it is better not to take risks and turn to a specialized service. Replacing the sensor is a relatively inexpensive procedure that will return your flagship full functionality.

Sometimes, a temporary solution in the form of software crutches, such as using a volume button to answer a call or turning on the sensitive In-pocket mode, if such an option is available in your version of firmware, helps, but these are only half measures that do not solve the root of the problem.

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