Modern Xiaomi smartphones are complex computing complexes hidden behind the friendly interface of the MIUI shell. However, to conduct a deep diagnosis or fine-tuning of the radio module, the user often requires access to hidden system partitions. One of these tools is an engineering menu that allows you to test hardware components without installing third-party software.
Owners of the Redmi Note 8 may have to check the quality of reception in a new area or the calibration of the display after changing the glass. This is where special people come to the rescue. USSD-commands and hidden codes that activate diagnostic modes.
Access to these features does not require root rights or unlocking the bootloader, which makes the procedure safe for the average user.The main thing is to clearly understand the purpose of each option so as not to accidentally change critical communication parameters. In this guide, we will discuss in detail all the available login methods and tools that the engineering console offers.
Purpose and capabilities of the hidden section
The engineering menu in Xiaomi smartphones is designed by developers to test the device in the production line, allowing isolated testing of individual modules, from the vibrator and speaker to GSM and Wi-Fi antennas. For the end user, it is a unique diagnostic tool that can detect hardware malfunctions before they become critical.
The CIT (Calibration Information Test) mode is especially relevant when buying a used device or after a gadget drops. You can run an automatic test of all components, and the system itself will point to the elements that work with errors, which is much more effective than relying on the subjective sensations of the touch screen or the auditory speaker.
⚠️ Warning: Changing settings in the Telephony or Common section without understanding their purpose may lead to network loss or radio module malfunction.
Among the key features, you can see detailed battery information, including the number of charging cycles and current capacity, which is often hidden in the standard menu, and you can also access advanced cellular signal monitoring, which shows the dBm level in real time, which is useful for finding a place with better coverage.
The main ways to activate diagnostic codes
The easiest and safest way to get into the hidden section is to use the standard Phone app. APK-You need to know the correct sequence of characters, which the system recognizes as a command to run a particular test.
For the Redmi Note 8, the most universal code is the combination ##6484##. Enter it in the dialing field, and you do not need to call the subscriber. Once you enter the last character, the interface automatically switches to the CIT screen, where you have a list of all available tests.
There is also an alternative way through the settings, which can be useful if the code does not work due to the features of the firmware version or region, you need to go to the About menu, find the kernel version line and quickly click on it 5-7 times, this action often opens up access to additional logs and tests.
- 📱 Entering code ##4636## opens the test menu where you can see the status of Wi-Fi and detailed network data.
- 🔧 ##6484## is the main combination for running a complete hardware test of components.
- 📡 Code ##3646633## (MediaTek) on some modifications opens access to the settings of the radio module, although on Snapdragon it may not work.
☑️ Check before entering the menu
Detailed analysis of the CIT (Calibration Information Test)
Once you've successfully entered the code, you'll see a list where each item corresponds to a specific node on your smartphone, and clicking on any item will start you to check it, for example, if you select TouchPanel, the system will ask you to swipe your finger around the circuits, which allows you to identify the "dead zones" of the sensor that are invisible in normal use.
The Receiver and Speaker test, which allow you to separate the speaker and the main speaker, often confuses a software failure with a breakdown, whereas simple diagnostics show that one speaker just got dirty or the contact of the plume broke away.
The Vibrator test checks the vibrator motor. The Redmi Note 8 uses a high-quality linear vibrator, and if you only feel a weak or no hum in this test, it's a direct sign that you need to replace the component, and you can also check all the volume and switch on buttons.
What to do if the test is not passed?
It's important to understand that some tests, like checking a camera or sensors, require certain actions: the camera can take a series of images with different shutter speeds, and the proximity sensor will require you to close the top of the screen with your hand. Auto Test can run the entire chain of checks without the user, but it takes longer.
Working with a radio module and setting up a network
One of the most popular features for advanced users is the Phone Information menu, available under the code ##4636##. Here you can see real information about connecting to the cell towers. You can see the type of network (LTE, 3G, 2G), signal level and even force the radio to switch modes.
In the Set Preferred Network Type section, you can lock your phone in LTE Only mode or turn off 4G if coverage is unstable in your region and the phone is constantly losing network.This often helps save battery power by preventing you from constantly searching for the best signal.
| Parameter | Description | Impact on work |
|---|---|---|
| Signal Strength | Signal level in dBm | The closer to 0, the better (normal -80...-100) |
| Cell ID | Cell ID | It allows you to identify a specific operator tower |
| IMEI | Unique device number | Necessary for registration in the network, check for blocking |
| Ping Time | Response time | Shows delay in data packet transmission |
Using this data, you can accurately diagnose communication problems: If the signal level is high (for example, -60 dBm), but the Internet is not working, the problem is most likely on the operator’s side or in the APN settings, rather than in the smartphone antenna.
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To reset network settings to factory settings without losing personal data, you can use the reset command in the radio module menu, but it is easier to do this through the “Reset settings Wi-Fi, mobile Internet and Bluetooth” in the regular menu.
Diagnostics of the display and touch layer
The screen is the most vulnerable design element of the Redmi Note 8. The engineering menu provides tools to check not only color rendering, but also touchscreen sensitivity. The Color test consistently paints the screen in different colors, helping to identify broken pixels or uneven backlighting.
TouchPanel involves drawing lines along specified circuits, a critical test after a protective glass is replaced or moisture is injected, and if a line is interrupted or twitched in a certain area, it indicates local damage to the digitizer.
⚠️ Note: When performing screen tests, make sure there is no dust or moisture on the display surface, as they may distort the sensitivity test results.
There's also a Multi-touch test that checks for multi-touch support, and the Redmi Note 8 has 10 simultaneous touches, and if the system registers fewer points, it could be a damaged plume or a screen controller.
Analysis of the battery status
The hidden menu allows you to access battery statistics, which are usually hidden from the user's eyes. Unlike the standard indicator, you can see the exact voltage, battery temperature and number of charge-discharge cycles.
Pay attention to the Battery Health option (if available in your firmware version) or indirect signs: if the phone turns off at 15-20% charge or heats up quickly when charging, these are signs of degradation of battery chemistry.
The discharge and charge test helps identify problems with the power controller. If the voltage jumps during the test or the charge current does not meet the stated specifications (for example, the Quick Charge fast charging is not activated), the problem may be in the USB connector or control board.
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Regularly checking charge cycles through the engineering menu helps to predict the battery life and replace it before bloating.