Modern Xiaomi and Redmi smartphones are complex computing devices in which software is inextricably linked to hardware. Sometimes users face situations when you need to conduct a deep test of the health of individual modules: microphone, speakers, touch screen or proximity sensors. Standard Android settings do not provide enough tools for such detailed diagnosis, so the company's engineers have implemented hidden partitions available through special commands. Transferring the device to diagnostic mode allows you not only to detect malfunctions, but also to calibrate equipment without contacting the service center.
Diagnostics, often referred to as CIT-The Customer Integrated Test is a powerful tool used in factories to control quality before selling, and activating this mode gives access to dozens of tests that check each component of the system for physical damage or software failures. This is especially true when buying a used device or after a phone crash, when external damage is absent, but the functionality is broken. It is important to understand that interference with system settings requires caution, since improper calibration can lead to incorrect operation of sensors.
In this article, we will discuss all the ways to activate diagnostic modes, review the functionality of the engineering menu and answer frequent questions that arise from owners of Xiaomi equipment. You will learn how to interpret the test results and what actions to take if errors are detected. A deep understanding of these processes will help you solve many technical problems on your own, saving time and money.
The main methods of activation of the diagnostic regime
There are several proven ways to get into the hidden parts of the system, each of which has its own characteristics and limitations. USSD-codes that work on most models, regardless of the firmware version MIUI Or HyperOS. To activate, you need to open the standard Phone app and enter the character combination. Once you type the last sign, the menu will open automatically, you don't need to click on the call button.
The second option involves using the About Phone menu, which is less versatile because it depends on the specific model and version of the shell, but it can be useful if the codes do not work due to carrier limitations or regional firmware features. In some cases, access is required. SIM-a specific operator or root right, although modern versions MIUI We try to minimize these requirements, and the engineering menu can also be accessed through the ADB-commands, but this requires a connection to the computer and the presence of debugging USB.
⚠️ Warning: Do not change settings in sections that you do not know the purpose of. Resetting the sensor calibration or changing the parameters of the radio module can lead to unstable operation of the device, which is difficult to fix without flashing.
The third way is relevant for advanced users and developers - the use of debugging applications or ADB-This method allows you to run specific tests automatically, which is convenient for mass testing, but for the average user, the easiest and safest thing is to enter code through a dialer. If the code doesn’t work, try re-entering it, making sure you don’t make any errors in numbers.
Using Secret Codes to Enter CIT
The most effective and quick way to activate the diagnostic mode is to enter a special code # # # #6484##. This combination is universal for the vast majority of Xiaomi, Redmi and other smartphones. POCO. Immediately after entering the last star on the screen will appear interface CIT, So each item corresponds to a separate test of the equipment, unlike the engineering menu, which is hidden deeper, CIT-The mode is visualized and understandable even to a beginner.
If the core code doesn’t work, which sometimes happens on global firmware versions or in specific regions, you can try an alternative combination of ##4636##. This code opens the Phone Information menu, which contains fewer iron tests, but provides critical information about battery status, usage statistics, and Wi-Fi network settings.
There are also specific codes for testing specific modules that can be useful in targeted diagnostics, such as ##2664## running a touchscreen test, and ##0*# (working on some models) opening a general display test, and knowing these combinations allows you to quickly check for a suspicious component without going through long lists of common menus.
Overview of functions and tests in the engineering menu
Once you successfully enter diagnostic mode, you have a long list of tests, each with a number and a name. The interface may vary depending on the version of MIUI, but the basic set of functions remains the same. Here you can check the vibrator, flash, all cameras (main, wide-angle, macro), microphones and speakers. Each test has its own algorithm: for example, when checking the screen, colors change to detect broken pixels, and when testing the touch screen, you need to swip your finger on a special grid.
Sensor tests are particularly noteworthy: Approximation sensor, accelerometer, gyroscope and compass are critical components for correct navigation, screen autorotation and face unlocking. In diagnostic mode, you can see raw data from these sensors in real time. If the phone's tilts do not change or change in snags, this indicates a need for calibration or hardware malfunction. Calibration is often solved by simply pressing the Calibration button inside the test.
☑️ Checklist of basic diagnostics
The menu also includes tests of communication modules, you can check the operation of GPS, Bluetooth, Wi-Fi and NFC. The system will try to find available networks or devices, demonstrating the strength of the signal and the stability of the connection. This helps to determine whether the problem with the Internet is software (driver failure) or hardware (burned antenna module), the test results are usually marked as “Pass” (successfully) or “Fail” (errort), which makes it easier to diagnose.
Table of main codes and their purpose
For the convenience of users, we have organized the most useful codes into a single table, and use it as a reference when you need to check a particular component of a smartphone, remember that the code is entered in the call app, and the result is displayed instantly.
| Code. | Function | Description |
|---|---|---|
| ##6484## | CIT Menu | Complete test menu for all components of the device |
| ##4636## | Testing | Information on telephone, battery and usage statistics |
| ##2664## | Touch Test | Checking the sensitivity and response of the touch screen |
| ##7780## | Factory Reset | Resetting settings (requires confirmation, deletes data) |
| *#06# | IMEI Info | Displaying serial numbers and IMEI devices |
These codes are safe to use unless you choose to reset. Codes like ##7780## can trigger Factory Reset, so be very careful when you press the buttons on the menu. Always double-check which command you are activating. Some codes may not work on devices without SIM-maps, as they are linked to network requests.
Diagnostics of the display and proximity sensors
Screen and sensor issues are one of the most common reasons for contacting the service, and in diagnostic mode, you can run a detailed Color Test that consistently paints the screen in red, green, blue and white. This allows you to identify not only broken pixels, but also uneven backlighting or "lights" along the edges of the matrix. OLED-screens are also important test for the uniformity of the glow of black pixels.
Touch Test requires fingers to run across all the grid cells, and if a zone doesn't respond or "gluts," it's immediately visible by the color changes in the cells, critical to detecting dead zones that can interfere with typing or playing, often after poor-quality repairs or cheap safety glasses that cause interference.
The proximity sensor often causes the screen to stay on the screen during a conversation, or the phone to not receive a call from your pocket. The diagnostic menu shows the current value of the sensor (usually from 0 to 5). When you cover the top of the screen with your hand, you should see the change in values. If there is no reaction, check if the sensor is closed with dirt, film or a case. The cleanliness of the upper frame of the smartphone is a key factor in the correct operation of the proximity sensor.
Audio system and communication modules
Audio tests in diagnostic mode allow you to check each microphone and speaker separately. Xiaomi smartphones often have several microphones (main, additional for noise reduction, headset). In the test mode, you can record the sound from each of them and listen to it. This helps to identify the quiet conversational speaker or wheezing main speaker, and also determine whether the noise reduction system is working.
Communication tests include GPS, Bluetooth and Wi-Fi. When you run a GPS test, the device will try to determine the coordinates. If the satellites are not indoors, go out into the open space. For Bluetooth and Wi-Fi, the phone will scan the air. The lack of visible networks with routers and devices nearby may indicate an antenna problem. The radio module is a complex component, and its diagnosis in CIT mode helps to separate the software glitch from the physical breakdown.
⚠️ Attention: When testing GPS Do not block the top of the smartphone with your hands, as this can shield the signal and give a false check result.
NFC testing is also available. If your model has this module, the test will show if the phone reads tags. This is useful for those who are actively using contactless payment, but have experienced sudden terminal failures. If the test does not pass, try removing the case, especially if it contains metal elements or magnets.
Frequent problems and methods of their solution
One common problem is that you can’t log in to the diagnostic menu, which may be because the Phone app has been replaced by a third-party app (like Google Phone or Truecaller) that doesn’t support processing. USSD-In this case, go back to the standard call. MIUI. If it is removed, it can be restored through resetting settings or installing a stock APK-file.
Another problem is the sticking in diagnostic mode, and sometimes the phone doesn't come out of the test, especially if the automatic check cycle is running, and then a long power button (10-15 seconds) to force the reset helps, and you don't have to panic if the screen goes out or the device vibrates, which is part of the test scenarios, and the key is not to take the phone apart during the test cycle, so as not to damage the plumes.
False sensor readings are often solved by simple calibration. In the CIT menu, select the appropriate test (like Proximity Sensor) and press Calibration. Follow the instructions on the screen: usually close the sensor with your finger, then remove your hand. After a successful calibration, the word "Pass" will appear. If the calibration does not help, the problem may be a software conflict or physical damage.