Calibration of the proximity sensor on Xiaomi Redmi Note 8: the full guide

The problem of the Xiaomi Redmi Note 8’s screen turning off during a conversation or not turning off when it is held to the ear is one of the most common complaints of the owners of this popular model: It is not just a minor inconvenience, but a serious functional error that can lead to accidental dialing of numbers with the cheek or interruption of an important conversation. In most cases, the reason lies in a software failure that requires correct calibration of the sensor, but we should not exclude physical contamination or defects in the protective glass.

Before you bring your device to the service center, you should try to restore the system yourself, as in 80% of cases the problem is solved by software methods. The MIUI Engineering menu provides access to hidden testing functions that allow you to fine-tune the sensitivity of the Proximity Sensor. Below we will discuss in detail all the available diagnostic and configuration methods to make your Redmi Note 8 work perfectly again.

The reasons for the incorrect operation of the sensor on the Redmi Note 8

The main reason for the approximation sensor failures is often the design features of the Redmi Note 8. The sensor is located at the top of the screen, and even minimal contamination, greasy fingerprints or dust can block its operation. In addition, black-framed protective glass or poor quality film often overlap the work area, which causes the system to receive false signals that the phone is near the ear.

Software conflicts also play a role: After updating the MIUI operating system or installing third-party applications to manage calls, the sensor settings can get lost, and in some cases, the background processes begin to process data from the hardware modules incorrectly, leading to the screen sticking off.

Physical damage, such as bumps or falls, can displace the plume or disrupt the contacts of the module itself. If software calibration does not help, you may need to deeper intervention in the hardware of the device, but you should always start with software methods.

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Before starting any work, be sure to wipe the top of the screen with a microfiber dipped in an alcohol solution to exclude the influence of external contaminants.

Diagnostics through CIT Engineering Menu

The most reliable way to check the status of the sensor is to use the built-in CIT (Customer Integration Test) menu, which is available on all Xiaomi devices and allows you to test each component separately.

To run a diagnosis, open the standard Phone app and enter a special code. You'll see a menu that lists all the tests available on the screen. You'll need to find a item associated with the Proximity Sensor and run it. During the test, the indicator will light up and the screen will respond to overlapping the top zone of the display.

If the screen does not go out during the test when the sensor is closed with the finger or, conversely, it goes out chaotically, this confirms the need for calibration. Note the readings in digital form: in normal state (the sensor is open), the value should be close to 5.0, and when closed, it should fall to 0.0.

Step-by-step instructions for calibration of the sensor

If the diagnosis shows a deviation, you need to perform a calibration procedure, which takes no more than two minutes, but requires accurate follow-up, and it is important to ensure that the phone is stable and there are no bright light sources aimed directly at the top of the device.

In the CIT test menu, after selecting the Proximity Sensor, press the "Calibration" button. The system will ask you to close the sensor with your finger or palm. Hold your finger tightly but without undue pressure until the successful completion message appears on the screen. Then remove your finger and confirm that the sensor is open.

Once you have successfully calibrated, the phone will automatically restart or prompt you to manually do so. If you don't automatically reboot, force it through the Settings menu → About Phone → Reboot. This is necessary to apply the new sensitivity settings.

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Successful calibration captures new sensitivity thresholds in the device’s memory, ignoring previous erroneous data.

Alternative methods through system settings

Some versions of the Redmi Note 8's MIUI firmware offer a simplified setup method through the standard menu, less accurate than CIT, but can help with minor crashes, and go to the call settings and find the point that handles the proximity sensor.

Sometimes it helps to simply reset your network settings and calls. Go to Settings → Applications → All apps, find the Phone app and select Clear → All data. This action will delete your call history, but return the sensor's factory settings.

Also worth checking for system updates. Xiaomi developers regularly release patches that fix hardware bugs. Go to Settings → About Phone → MIUI version and click the update check button.

⚠️ Warning: Clearing the phone application data will delete all call history, and it is recommended to save important numbers in advance or synchronize them with the Mi Account acca.

Influence of accessories and protective glasses

A common cause of sensor problems on the Redmi Note 8 is the wrong security glass. Many users choose perimeter black frames that can overlap the sensor element. Visually, this may be invisible, but for an IR sensor, it is an insurmountable barrier.

If you recently put on a new glass or film and the problem came immediately afterward, try carefully removing the accessory and checking the sensor. 9 out of 10 cases, the problem lies in the thickness or dimming of the protective layer above the sensor area.

Quality glass for Xiaomi usually has a special cutout or transparent zone at the top. Using cheap analogues without taking into account the location of the sensors often leads to constant failures in the screen during a conversation.

Table of codes and commands for diagnosis

For advanced users and professionals, there is a set of commands that allow you to access hidden functions. Below is a table of basic codes that are relevant to the Redmi Note 8 model and most MIUI-based devices.

What to do if calibration does not help

If all software methods, including factory reset and flashing, fail, there is a possible hardware malfunction, which could be a plume break, oxidation of sensor contacts, or failure of the Proximity Sensor module itself.

In such cases, you need to disassemble the device. On the Redmi Note 8, the sensor is integrated into the display plume or located on a separate board under the speaker, you need to check the connection of the plume to the motherboard and clean the contacts with ultrasound or alcohol.

If you do not have the skills to repair electronics, it is better to contact a specialized service. Self-disassembly can damage the display or violate the tightness of the case, which will deprive you of warranty.

⚠️ Warning: Disassembling your smartphone will void the manufacturer's warranty. If the device is in warranty service, contact an authorized center.

Frequently Asked Questions (FAQ)