How to calibrate and repair your smartphone's proximity sensor

¿How to calibrate and repair your smartphone's proximity sensor? If you've ever accidentally hung up a call, activated the speakerphone, or opened strange menus just by holding your phone to your ear, chances are the culprit is the smartphone proximity sensorIt's a tiny component that we almost never pay attention to, but when it fails it can turn every call into a real nuisance.

The good news is that, in most cases, these problems can be mitigated or even resolved by adjusting, resetting, or calibrating the sensor, without having to go directly to a service center. This guide provides a complete explanation of What is a proximity sensor, how does it work, what types are there, and what to do step by step when it starts to cause trouble, with special attention to Android phones and, above all, models from Xiaomi, Redmi and POCO.

What is the proximity sensor and what exactly does it do on your mobile phone?

In a modern mobile phone, the proximity sensor is a small transducer that detects objects very close to the front of the device. Its main function is to automatically turn off the screen and disable the touch function when you bring the phone to your ear during a call or when playing voice notes in apps like WhatsApp or Telegram.

By turning off the screen and blocking touches, accidental presses are prevented: You don't put the call on hold, you don't activate the speakerphone, and you don't hang up with your face visible.In addition, it usually works together with the ambient light sensor and other components to adjust energy consumption and panel behavior.

This component is usually located at the top front of the mobile phone, near the earpiece, although In many models with very thin bezels, it is integrated under the panel itself.On some recent Galaxy and Xiaomi phones, and other mid-range and high-end phones, the sensor is "hidden," which makes adjusting it a bit more complicated and more sensitive to cases, poorly fitted screen protectors, and dirt.

Classic designs employ an infrared optical system, in which an emitter launches a IR light beam bouncing off your face A receiver measures the reflected light. When the signal exceeds a certain threshold, the system understands that something is attached to the phone and turns off the screen. However, this is not the only technology involved.

In recent years, some manufacturers have replaced this physical sensor with “virtual” systems that rely on ultrasound and other sensors such as the gyroscope or accelerometerThis lowers costs and reduces components, but also opens the door to more calibration failures and erratic behavior.

Types of proximity sensors and related technologies

In electronics, there are several ways to detect proximity. Many are used in robotics or industry, and only a few have ended up integrated into smartphones. Understanding them helps identify where problems might arise and what adjustments make sense.

Infrared photoelectric sensor

It is the most common type in mobile phones with a physical sensor. It consists of an infrared light emitter and a receiver (photodiode or phototransistor) that measures the amount of light reflected by a nearby objectThe circuit processes that signal and converts it into a binary value: object near / object far.

In industrial environments, these sensors can use coded signals to distinguish its own beam from ambient light or share the receiver among several transmitters. On a phone, the implementation is simpler, but the logic is the same: if it detects enough reflection in a very close area, the system turns off the screen and blocks the touchscreen.

Ultrasonic sensors

Ultrasonic sensors emit high-frequency sound pulses, inaudible to the human ear, and measure the echo that returns after bouncing off an object. By measuring the time and intensity of that echo, the approximate distance is calculated.

In robotics, they can detect obstacles from several meters away, but in mobile devices, they are used at short distances and combined with software and other sensors (such as gyroscopes and microphones). This approach allows for dispensing with the classic optical sensor, but It relies heavily on fine calibration algorithms and it is more susceptible to noise, the position of the phone, or certain cases.

Magnetic sensors and other nearby sensors

Magnetic proximity sensors are also used in industrial automation, capable of detect magnetized objects even through non-magnetic materialsThey are used as limit switches, door opening detection, and similar applications.

In mobile phones, the magnetometer acts as a digital compass and does not function as a proximity sensor for calls. It should not be confused with the system that turns off the screen, although it is part of the sensor ecosystem in modern smartphones, along with... accelerometer, gyroscope, barometer, light sensor, battery, temperature, fingerprints and others.

Physical sensors versus virtual proximity sensors

Many current Android phones, especially some Xiaomi, Redmi and POCO models, have made the leap from a dedicated optical sensor to a virtual proximity system based on ultrasound and softwareThe best-known case is the technology of Elliptic Labs (INNER BEAUTY), massively integrated between 2020 and 2022.

In these devices, the phone emits an ultrasonic signal from the top of the screen towards your head. The secondary microphone picks up the echo and, if it arrives earlier or with greater intensity than expected, The system interprets that there is something stuck to the phone. and turn off the panel. The gyroscope helps by detecting the gesture of bringing the phone to your ear.

This approach has clear advantages: it reduces frameworks, lowers production costs, and eliminates physical components. The problem is that it is much more delicate than a classic optical sensorChanges in posture, ambient noise, thick cases, or poor factory calibration can cause the screen to not turn off when it should, or to do the opposite and go black for no apparent reason.

Xiaomi, Redmi and POCO models with more proximity problems

A large portion of the complaints about proximity sensor failures have been concentrated in Xiaomi phones released around 2020, when the brand heavily invested in virtual sensors instead of optical components. Many users began to notice that The screen wouldn't turn off during calls or it would turn on by itself with any movement..

Among the models with the most reported issues are the following very popular devices:

• Xiaomi Mi 10T
• Xiaomi Mi 10T Pro
• Xiaomi Mi 10T Lite
• Xiaomi Mi Note 10 Lite
• Redmi Note 10
• Redmi Note 10 Pro
• Redmi Note 9
• Redmi Note 11
• POCO M4

In many of these phones, and in models like the Redmi Note 15the sensor is integrated under the screen and controlled almost entirely by MIUI or HyperOSXiaomi itself even opened public surveys to gather data on the frequency of the failures, in which apps they occurred (phone, WhatsApp, etc.) and under what circumstances, with the idea of ​​polishing the system through updates.

Typical symptoms when the proximity sensor fails

When the proximity sensor, physical or virtual, starts malfunctioning, the phone makes it quite clear. The most obvious sign is that The screen doesn't turn off when you bring the phone to your ear. during a call or when playing voice notes.

In that situation, it's very easy to accidentally hang up, turn on the speakerphone, mute the microphone, access hidden menus, or randomly tap icons with your cheek. Many people don't realize the sensor is to blame until they consciously try it.

The opposite can also happen: a incorrect factory setting This causes the system to interpret that something is nearby when it isn't. The result is a screen that turns off too soon or doesn't turn on when you move the phone away from your head, forcing you to press buttons to regain control.

Another very common issue is problems listening to WhatsApp or Telegram audio messages. The phone should switch from the external speaker to the earpiece as soon as you bring it to your face and return to the speaker when you move it away. If the calibration is poor, the audio will cut out, decrease in volume for no reason, or switches speakers erratically.

Added to this are messages that generate confusion, such as the warning "Do not cover the earpiece area." This warning refers primarily to Do not cover the earpiece speaker with your hand, a case, or any other object.This does not necessarily imply a failure of the proximity sensor, even though both elements share a physical location.

External factors that impair detection

Before getting bogged down with secret codes and developer menus, it's best to check for the simplest causes: dirt, improperly fitted cases or screen protectors. In many phones, the problem is more related to maintenance than hardware.

The upper part of the front panel, where you rest your ear, fills up easily with grease, dust, sweat, makeup, and product residueOver time, that layer can partially block infrared light or distort ultrasonic signals.

Ideally, that area should be cleaned periodically with a microfiber cloth and some isopropyl alcoholIt evaporates quickly and usually leaves no residue. If the dirt is very stubborn, you may need to work at it a little longer, always being careful not to press too hard or get liquid in crevices.

Cases and screen protectors also bear some of the blame. If they aren't properly designed for your specific model, it's easy for the cutout in the protector or the edge of the case to get damaged. invade precisely the area where the sensor worksOn some phones with under-display sensors, an overly thick screen protector can change how light or ultrasound is reflected.

If you suspect these accessories, try temporarily removing the case and screen protector, restarting the device, and making several test calls. If things suddenly improve, It's time to change the accessories for ones specifically designed for your model..

Is it necessary to calibrate the sensors on Android?

Google Play is full of apps that promise to "calibrate all sensors" with a magic touch, but the reality is more prosaic. Most sensors come They are factory calibrated and don't lose their references just like that., except for physical damage or serious software errors.

In addition, calibration parameters are usually stored in protected system partitionsTo truly modify them, root access or system permissions would be required. Regular apps, which don't require superuser privileges, have very limited capabilities: they are usually limited to running tests, resetting internal caches, or applying fixes within the app itself.

Therefore, when we talk about calibrating the proximity sensor, it is much more reliable to use official system tools, manufacturer's test menus (like Xiaomi's CIT) or developer options, instead of relying on miracle solutions.

Specialized diagnostic apps are indeed useful for measuring and checking if the sensor is responding: they allow you to see how the proximity value changes when you cover the top of the phone, which helps to distinguish between hardware failure and configuration or software problem.

How to see which sensors your mobile phone has and check if they respond

If you want to know precisely which sensors your device has (including the proximity sensor) and verify if they are responding, the most practical thing to do is to install tools like Multi-tool sensors, sensor boxes, or similarThese apps read and display the values ​​delivered by the sensors in real time.

With them you can confirm if your mobile phone has gyroscope, barometer, magnetometer, ambient light sensor, proximity sensor, and othersAdditionally, by covering the sensor area with your hand, you should see the proximity value change, for example from 5 (uncovered) to 0 (covered), or a "near/far" state.

If the value doesn't change no matter what you do, and the rest of the sensors are working correctly, it's quite likely that there's a problem. physical failure in the proximity component or a deep firmware problemHowever, if the value responds in these apps but not during calls, the problem points to the software layer (phone app, customization layer, permissions, etc.).

Activate or deactivate the proximity sensor on Xiaomi phones (MIUI)

Many Xiaomi phones with MIUI have a specific switch in the call settings for activate or deactivate the use of the proximity sensorIts exact location has changed depending on the version (MIUI 11, 12, 12.5, HyperOS…), but it is still present in many models.

If your phone doesn't turn off the screen during calls, the first thing to check is that the sensor is enabled in that menu. The typical path in MIUI is:

• Open Configuration (Adjustments).
• Go into System application settings.
• Gonna Call settings.
• Access Incoming call settings.
• Verify that the option of proximity sensor It is active.

A useful trick is to temporarily disable that switch, restart your phone, and then re-enable it. This cycle usually forces MIUI to reapply default sensor parameters And, in many cases, it causes the behavior to return to normal without the need for further steps.

Calibrate the proximity sensor on Xiaomi using the CIT menu

Most Xiaomi, Redmi, and POCO phones include a service menu called CIT that allows you to test and, in some models, calibrate sensors and internal components. It's the official tool you should use before considering third-party apps.

To open the CIT on many recent devices, simply:

• Open the original phone application.
• Enter the code *#*#6484#*#* (The menu will open automatically once you finish typing it).

Within the CIT you will see a list of numbered tests. You must locate the entry called “Proximity Sensor Test” or “Proximity sensor”, which is usually around numbers 20-30, although the exact position varies by model.

Once inside the test, the basic procedure is:

• Cover the top of the front of the mobile phone, where the sensor is located, with your hand.
• Observe the value displayed on the screen: if It goes from 5 to 0 when covered and returns to 5 when uncovered.the sensor detects the changes.
• If there is a button CalibratePress it and follow the instructions.

On some models, the calibration button doesn't appear directly in that test. In that case, tap the icon of three points From the top right corner, go to “Additional tools” or “Additional Tools”, where there may be an extra section for “Proximity sensor” to adjust sensitivity and other parameters.

Recalibrate the proximity sensor step by step in MIUI

On Xiaomi devices where the CIT offers the "Proximity sensor calibration" function, a near-automatic sensor recalibrationBefore starting, thoroughly clean the top of your phone and remove the case and screen protector if you suspect they are in the way.

The general process is:

• Dial *#*#6484#*#* to enter CIT.
• Open the proximity sensor test and confirm that the value changes when covering/uncovering.
• Tap the three dots and look for the option “Proximity sensor calibration”.
• Place the phone on a flat surface, with nothing in front of the sensor, and run the calibration.

After completing the process, it is recommended to Restart the device and make several test callsIf the problem was a parameter mismatch, you should notice more consistent behavior: the screen turns off and on when it touches.

Reset all sensors from developer options

Android doesn't include a direct "reset proximity sensor" button, but it does have a hidden function to do so. Temporarily disconnect all sensors and then reactivate them, which is equivalent to a small general reset.

To use it, you must first enable developer options:

• Go to Settings > About phone.
• Locate the Compilation number (or Build Version) and press repeatedly until the system confirms that you are a developer.
• Go back to Settings and enter System > Developer options (The route may vary depending on the brand).

Within that menu, use the search bar to find the option “Sensors deactivated”When activated, a new icon will appear in the quick settings panel.

When you tap that icon, your phone will turn off readings from all sensors: motion, temperature, battery, and, of course, proximity. After a few seconds, tap it again to Reactivate the sensors and complete the reset cycleIf the error was due to strange software behavior, this trick usually helps to rectify the situation.

Other practical solutions before restoring your mobile phone

If, despite cleaning, checking the case and screen protector, activating the sensor in the call settings, recalibrating with the CIT and restarting the sensors, you are still having problems, you still have some options before performing a complete wipe.

The most basic thing is restart smartphoneIt sounds like a cliché, but often an internal process gets stuck and affects the sensor's behavior. Turn your phone off, wait a few seconds, and turn it back on; then, make a couple of test calls.

Next, check if there are system updates availableOn Xiaomi devices, you can go to Settings > About phone and tap on the MIUI or HyperOS version to check for newer versions. Many proximity issues in recent models have been fixed via OTA updates.

Another highly recommended test is to start the device in Android safe modeThis startup temporarily disables all third-party apps. If the sensor works correctly in safe mode but fails again upon normal startup, it's almost certain that An application you have installed is interfering..

Several Xiaomi devices also offer the option to Reset only settings and app data Go to Settings > Additional settings > Factory data reset, choosing the option that doesn't delete photos or personal files. If the problem is related to settings, this light reset might work wonders.

When to perform a full restoration or seek technical support

If, after trying all of the above, the sensor still does not respond or behaves absurdly, it is time to consider more serious measures: Reset the phone to factory settings or go to a service center.

If you decide to restore, first make a full backup of your data (photos, videos, documents, chats, etc.). Then go to Settings > Backup and reset (or equivalent) and select the option to erase all content from the phone.

After completing the reset and setting up the phone from scratch, try the proximity sensor with a call before installing your apps or restore large backups. If the problem persists in that "clean" state, it's a pretty clear sign that there's a hardware issue or a design flaw in the model.

In that case, the reasonable thing to do is to go to official technical service or a trusted workshopIn the European Union, new mobile phones have several years of legal warranty for defects in conformity, so if the problem is not caused by bumps, drops or liquids, the manufacturer should take responsibility.

Deactivating the proximity sensor: when it makes sense

It may be surprising, but some users prefer to completely disable the proximity sensor. Some do this because privacy concerns, due to distrust of how certain apps could exploit that data to analyze usage habits, screen time, or gestures.

Others simply get fed up with audio cuts in voice notes or automatic speaker changes when they move the phone, and prefer the panel to stay on and the sound to always come from the same place. However, disabling the sensor involves... assume the risk of unintentional touches during calls.

In many XiaomiTo deactivate the sensor (if your model allows it), simply follow this path:

• Settings> Applications.
• System application settings.
• Call settings > Incoming call settings.
• Turn off the switch proximity sensor.

If your phone doesn't show that option, it may be using an always-on physical sensor or a low-level managed virtual solution, without a visible switch. In those cases, you'll need to resort to the other solutions described or, if nothing works, to technical support..

Although this component is tiny and doesn't attract attention, keeping the sensor area clean, using appropriate cases and protectors, taking advantage of the manufacturer's test and calibration menus, and keeping the system up to date often makes the difference between a phone that frustrates you on every call and one that simply does what it has to do without giving you problems.