Xiaomi turns off when you call: a full analysis of the problem

When your Xiaomi suddenly goes out at the exact moment of incoming or outgoing call, it can be taken by surprise at the most inopportune moment.It is not just an annoying bug, but a potentially serious signal of malfunctioning of software algorithms or hardware of the device. Often users confuse the actual turn off of the smartphone with emergency screen cancelling, which leads to false conclusions about the need for complex repairs.

There are many factors at the heart of the problem, from the trivial sticking of the proximity sensor to the critical wear of the battery, which can not withstand peak loads when the radio module is activated. Understanding the exact cause is the first step to restore normal operation of the gadget. In this article, we will analyze all possible scenarios in detail and provide step-by-step instructions for their elimination.

Before you bring your device to the service, you should do your own diagnostics, which in most cases helps to identify the root of evil. Repair statistics show that more than half of the cases with such a problem are solved by software methods or replacing inexpensive consumables. Don't panic if your phone behaved strangely, because system failures are common.

Approximation sensor: the main suspect

The most common reason Xiaomi's screen goes out during a conversation is the incorrect approach sensor.This small sensor, located at the top of the display, is responsible for turning off the backlight when you hold the phone to your ear to prevent accidental cheek pressing. If it's contaminated or malfunctioning, the screen can go out instantly and not turn back on.

Often the problem lies in the protective glass or case, which overlaps the sensitive area. Even a thin film can shift and cause interference. It is also worth checking the calibration settings, because after a drop or update of the firmware, the sensor parameters can get lost. In some cases, the usual cleaning of the area around the speaker from fat and dust helps.

To test the sensor, you can use an engineering menu that's hidden from the user, so you can see if the sensor is responding to the hand being brought to the screen, and if the response is not correct, you need software or hardware calibration.

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Before calibrating the sensor, be sure to remove the protective glass and thoroughly wipe the top of the screen with an alcohol napkin to exclude the influence of external factors.

If software methods don't work, maybe the sensor plume itself, which is often assembled with the speaker, has failed, so replacing the module will solve the problem once and for all. Note that on models with AMOLED screens, the sensor can be built directly into the matrix, which makes it difficult to diagnose.

Problems with battery and contacts

The second most common cause of sudden shutdowns is the battery state. During an incoming call, the smartphone goes into active radio mode, which creates a sharp jump in power consumption. If the battery is worn out, its residual capacity may not be enough to maintain voltage under load, leading to an emergency shutdown of the device.

This is especially true in cold or under 20%. Older lithium-ion batteries lose their ability to deliver peak power current. It's also worth checking the battery and plume that goes to the motherboard. Oxidation or weakening of the connection can lead to short-term circuit breaks when vibrating or heating.

You can diagnose the battery status through special applications or engineering menus. Pay attention to the voltage: if it drops below 3.4-3.5 Volts under load, it is time to change the battery, ignoring this symptom can lead to bloating of the battery and damage to other components.

Failures in the MIUI operating system

Mistakes in the MIUI shell can also cause phone behavior to be incorrect during calls, process conflicts, errors in radio module drivers, or malfunctioning applications can trigger a reboot or turn off the screen, especially after updating firmware or installing applications from unverified sources.

One common cause is a crowded cache of the Phone or Contacts system application. Temporary files can cause incoming call processing to malfunction, and it’s worth checking if you have a modified kernel or third-party themes that may conflict with standard system functions.

⚠️ Note: Installing custom firmware or obtaining superuser rights (Root) can disrupt the radio's stable work module. If the problem occurs after such manipulations, go back to the stock version of the software.

To eliminate software errors, it is recommended to clean the cache and, if necessary, completely reset the settings.Be sure to back up important data before that, sometimes it helps to simply update the system to the latest available version, where known bugs are fixed.

The Impact of Third-Party Applications and Conflicts

Third-party applications that have access to microphones, contacts, or call functions can interfere with the normal interface, and various number detectors, call recorders, or smart spam blockers can often be the culprits of unstable work, and can intercept screen control or cause errors in communication processes.

To identify the culprit, try running your phone in Safe Mode, which is only the system applications that are downloaded, and if the safe mode is normal, then the problem is with third-party software, and by eliminating uninstall-yet newly installed programs.

Special attention should be paid to applications that control the screen or lock, and some “battery savers” or “antiviruses” can aggressively close the background processes, including the telephony process, which is perceived by the system as a critical error.

Hardware malfunctions of the motherboard

If software and battery replacement didn't work, the problem probably lies deeper in the hardware of the motherboard, and microcracks in soldering of the processor, modem, or power controller can occur when the device is heated during a conversation, and thermal expansion of materials leads to loss of contact in the problem area.

This is often a problem that occurs after falls or moisture, and even if the phone is intact, there may be a chip dump inside, and the diagnosis of such malfunctions requires professional equipment and a microscope, and self-repair can lead to complete destruction of the device.

Another reason could be a malfunction of the radio module itself or the antenna unit, and if the antenna contact is oxidized or the antenna plume is damaged, the phone will try to increase the signal power, overheat and shut down, which is a protective reaction of the system to overheat the components.

⚠️ Attention: Attempts to warm up the motherboard with a hairdryer at home without the appropriate skills and fluxes most often lead to the final failure of the board.

Network settings and SIM-map

Sometimes the reason is not the phone, but the SIM-- the map or network settings of the operator. SIM-cards that do not support modern encryption standards or 4G/LTE, It can cause network log-in failures during a call, and it can also be a problem with an incorrect network profile.

Try to extract SIM-map, wipe contacts and insert into another slot (if there are two) to check if you have a forced mode only in the case of a computer. 4G or 3G. Switching to “Preferred” mode 4G/LTE» Or "auto" can stabilize the connection.

It is also worth checking the VoLTE settings. If your carrier supports this technology but it is not configured correctly, the transitions between voice/data modes can cause crashes. SIM-map.

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Replacement of the old SIM-The card for the new in the cabin operator often solves the problem of sudden communication breaks and shutdowns, as new cards have improved contact and support for modern protocols.

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