Xiaomi and Redmi’s modern smartphones have powerful diagnostic tools that are not available to the average user by default: an engineering menu designed to test hardware components in the factory and in service centers, which allows you to conduct deep checks of the microphone, screen, proximity sensors, and even change the display parameters of the interface.
Entering this section requires caution, as changing critical parameters can lead to unstable operation of the MIUI or HyperOS operating system. However, if you want to diagnose a malfunction yourself or simply hide the notch under the camera ("bangs") in the status bar, knowing these secrets will be extremely useful.
You should understand that the engineering mode is not a toy, but a professional tool. Although you can get there with a standard phone dialer, the internal settings are divided into safe and potentially dangerous. In this article, we will focus on those options that will help you set up the device or check its condition without the risk of turning the smartphone into a brick.
What is an Engineering Menu and Why You Need It
The engineering menu, often called the CIT (Customer Integration Test), is a hidden part of the Android operating system, and its main purpose is to allow you to run automatic hardware component tests, and when you buy a new phone, it's through this interface that the factory checks whether the touchscreen is working, if there are broken pixels, and if the sensors are properly calibrated.
For the average Xiaomi smartphone owner, this section opens up possibilities beyond standard settings, such as forcing a specific frequency vibration test or checking all volume buttons. Diagnostics through built-in system tools are often superficial, while engineering mode allows access to hardware directly, bypassing the software limitations of the shell.
But the menu isn't limited to tests, and some firmware versions have settings that affect how the status bar displays, and the Notch is one of the most popular features that users are looking for when they want to make the interface more seamless, and you can find information about the exact battery voltage and the real-time temperature of the processor.
How to log in through codes and app
There are several proven ways to activate hidden diagnostic mode. The fastest and most versatile method for all Xiaomi, Redmi and Poco devices is the use of special devices. USSD-You don't have to install third-party software or get root rights, just type in a sequence of characters.
Open a standard caller and dial the code ##6484##. If the combination is entered correctly, the system will automatically redirect you to the test menu, and you do not need to dial the call button. On some global firmware versions or in new HyperOS updates, this code can be changed to ##64663##. If none of the codes worked, try the option ##4636#, which opens the phone information menu, which is part of the engineering menu.
☑️ Checking before entering
An alternative route is through the standard settings menu, which is especially relevant if the phone's keyboard doesn't recognize special characters or the code just doesn't respond. Go to Settings → About Phone → Version of the kernel. A quick five tap on the "kernel version" line should trigger the CIT menu.
⚠️ Note: If nothing happens after entering the code, it is possible that your shell version MIUI I blocked this entry. So try installing the app"CIT" from unofficial sources, but do so only from trusted repositories.
Main functions and tests of equipment
Once you log in, you'll see a list of tests sorted by component, each point is responsible for checking a particular node on a smartphone, for example, the Touchpanel test allows you to check the response of a screen across its entire area by drawing lines with your finger, which is a great way to detect dead zones that are not visible in normal use.
The Speaker and Receiver section plays audio files through the main and conversational speakers respectively. This helps you know if the sound is wheezing at maximum volume. The Vibrator test makes the device vibrate, which is useful for assessing motor wear, especially if you feel that the recoil has become weaker.
Below is a table of the main tests and their assignments so you can navigate the long list faster:
| Name of the test | Function | What we check. |
|---|---|---|
| Key | Button checks | The operation of the volume and power buttons |
| Touchpanel | Touchscreen test | Screen response, presence of broken zones |
| RGB | Color rendering | The presence of broken pixels, lights |
| Proximity | Approximation sensor | Responding to face-to-face presentation |
| Battery | Status of AKB | Temperature, Voltage, Charge Status |
It is important to note that Proximity is often used for calibration, and if your screen stops turning off while you're talking or goes out while watching a video, running that test and following the instructions on the screen (close the top with your palm and remove it) can solve the calibration software failure.
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If the proximity sensor test shows Fail, wipe the top of the screen over the speaker, often with greasy marks or a protective glass blocking the sensor.
How to hide the screen cutout (Notch) in MIUI
One of the most popular features of the engineering menu for smartphone owners with bangs is the ability to change the display of bangs. Standard Android settings often give no choice, leaving a black bar or notch. Through a hidden menu, you can forcibly hide this area, making the status bar solid.
To do this, log into the engineering menu and look for Notch or Display (names may differ in different versions of firmware, sometimes just Current Notch). Inside, you'll see options: Default (default), Hide Notch (hide) and Remove Notch (delete/show). The Hide Notch mode choice paints the area around the cutout black, visually hiding it.
Once you select the right setting, you need to restart the device. Only after the full on-off and off cycle (Reboot) changes will take effect. If the effect does not appear the first time, try to switch the mode back to Default, restart again, and then repeat the hiding procedure.
⚠️ Note: In some models with AMOLED-The screens hide the cutout can cause the pixels at the top of the screen to burn out unevenly, as they will work with different brightnesses.
What to do if there is no Notch item?
Diagnostics of battery and network
The power and communications section contains technical information that is difficult to obtain in other ways. Unlike the standard percentage indicator, you can see the actual battery voltage here. A value between 3.7V and 4.2V is considered normal depending on the level of charge. If the voltage drops below 3.5V at 20% charge, this is a sign of battery wear.
Also available here is detailed information about the cellular network. Phone Info menu (often called by code ##4636##) can switch the preferred network type, for example, force LTE Only to be set if 3G catches better in your area and 4G constantly loses signal, which can help stabilize the connection in areas of uncertain reception.
Temperatures are also displayed in real time, you can see the heating of the processor (CPU Temp) and the battery. If the temperature is above 40 degrees in idle mode, this is an occasion to check the background processes or the state of the thermal paste / heat sink inside the device.
For those who are engaged in deeper customization, a selection menu is available. SIM-Data cards and voice calls, even if the standard interface limits these capabilities, but beware: resetting network settings through this interface (Reset Radio) can temporarily shut down mobile communication until the next reboot.
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Forced switching to LTE Only mode can save battery life in low signal areas by preventing a constant search for 3G/2G networks.
Possible risks and precautions
Despite its usefulness, the engineering menu is a zone of increased responsibility. Changing the parameters in sections labeled as Debug or Factory can lead to software failures. For example, resetting the sensor calibration without professional equipment can make the touchscreen insensitive or, conversely, too sensitive to touch.
It is particularly dangerous to touch settings related to IMEI and base radios. Changing these sections can cause a signal to be lost or the device to be blocked by the operator. If you are not 100% sure of the specific option's purpose, you should leave it unchanged. The "don't know, don't touch" rule works flawlessly here.
If your phone starts to behave incorrectly after your experiments (the sound is gone, the microphone is not working), the first thing you do is reset the settings completely through the Recovery Mode menu, which will return the software settings to factory values, but will not affect your personal files unless you select the "Wipe All Data" option.
⚠️ Warning: The Engineering Menu is not designed to unlock the Unlock Bootloader. Trying to find such features here is pointless and can lead to system errors.