Xiaomi’s smartphones, including the popular Redmi Note 8, have hidden functionality that is usually closed to the average user, a hidden section of the Android operating system called the Engineering Menu, or CIT, which is a diagnostic tool created by factory engineers to test hardware components before being shipped to the market.
Gadget owners often look for a way to get inside the system to test the performance of iron on their own after buying a used machine or after falling. Entering the engineering menu does not require superuser rights (Root), which makes the procedure available to anyone who knows the right sequence of actions.
Incorrectly changing the parameters in this section can lead to incorrect communication, failures in the display of colors or problems with the touch screen. In this guide, we will discuss in detail the safe methods of entry, we will discuss the basic tests for the Redmi Note 8 and explain which parameters can be touched and which are better left unattended.
What is an engineering menu and why it is needed
The engineering menu is a special software interface built into MIUI firmware, and its main purpose is to allow technicians in the factory to quickly check every module of the smartphone, from the vibrator to the communication modules, and for the average user, it is an opportunity to conduct deep diagnostics without connecting to a computer.
Unlike standard Android settings, this displays technical data that you can't see in normal mode. You can see the actual battery status, the exact coordinates of the touches, check for broken pixels on the matrix and test all the sensors. This is especially true for the Redmi Note 8, which is no longer new, and the status of its components may be questionable.
Using this tool, you can detect hidden defects that do not appear during normal use, for example, the microphone may work quietly, or the speaker may wheez at high frequencies, and in the engineering menu, these nuances are detected immediately when the appropriate tests are performed.
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Before buying a used Xiaomi Redmi Note 8 be sure to conduct tests in the engineering menu to avoid purchasing a device with hidden hardware defects.
It is worth noting that the menu interface may vary depending on the version of the operating system installed. On global firmware and Chinese versions of MIUI, the test set may vary slightly, but the basic functionality remains uniform for the entire ecosystem.
The main ways of entering through system code
The simplest and most common method of accessing a hidden menu is the use of a special menu. USSD-This method works on most Xiaomi devices and does not require the installation of additional software».
To start, open the call app, where you usually dial the number of the person you are talking to. In the digit input field, you need to enter a special combination of characters. For Redmi and Xiaomi devices, the universal code is ##6484##.
Once you enter the last character (star), the dialing will automatically stop, and the test interface will appear on the screen. If this does not happen, and the call went or the code just erased, then your carrier is blocking such requests or the firmware has restrictions.
☑️ Checking before entering
There is also an alternative code ##4636## that opens the test menu, but it's less informative for checking hardware and more suitable for setting up network types. For a full Redmi Note 8 diagnosis, use the first option.
Alternative methods through settings and ADB
If you don't get the code entry for some reason, you can try getting into the diagnostics menu through the standard settings menu, which is longer, but it's guaranteed to work on current versions of MIUI, and you'll need to be careful when you switch items.
Go to About Phone and find Kernel Version or MIUI Version, and quickly press 5-7 times on this item. In some firmware versions, this action opens a hidden menu, in others it just shows the system logo. If the menu doesn't appear, move on to a more complex method.
For advanced users, you can log in via USB debugging and a computer.
- 📱 Enable the developer mode by repeatedly clicking on the build number in "About phone».
- 💻 Activate the item “Debugging of the USB» In the Appearing Menu for Developers.
- 🔌 Connect your smartphone to a PC with installed ADB (Android Debug Bridge).
- ⌨️ The command is: adb shell am start -n com.android.settings/.SubSettings
Why can't the code work?
Using ADB gives you maximum control, but requires a computer and basic command line knowledge. For most Redmi Note 8 users, a standard code or settings menu will suffice.
A detailed review of available hardware tests
Once you're signed in, you'll see a list of tests. Each item corresponds to a specific module on your smartphone. For the Redmi Note 8, this list includes checking the camera, sensors, display and communication modules. Let's take a look at the most important ones.
The Receiver test checks the speaker speaker, you'll hear a horn or a synthesized speech, and the Speaker test checks the main multimedia speaker, and it's important to distinguish between the two, because users often confuse the breakdown of the speaker with the main speaker.
The Touchpanel touchscreen test is worth special attention, and when it starts, the screen turns black, and you need to swipe your finger across all the grid cells, and if a zone does not respond or a phonith (the line is drawn by itself), this indicates a malfunction of the digitizer.
Below is a table of the main tests and their purpose for the Redmi Note 8 model:
| Name of the test | Function | Normal result |
|---|---|---|
| Green/Red/Blue | Matrix verification | Uniform color without stains |
| Vibrator | Vibrio check | Sensible vibration |
| WLAN | Wi-Fi module test | List of available networks |
| GPS | Navigation check | Coordinates and satellites |
| Proximity | Approximation sensor | Reaction to the hand-off |
A GPS test is also available to see if the phone is seeing satellites, and the signal in the room may be weak, so it's best to go outside or go to the window for an accurate check.
Diagnostics of the display and sensor Redmi Note 8
The screen is one of the most important and fragile elements of the Redmi Note 8. There are several items on the engineering menu dedicated to its verification. Tests Red, Green, Blue and White allow you to pour the screen in a monochromatic color.
This is necessary to identify broken pixels (dots that do not burn or burn in a different color) and lights. Carefully examine the matrix in bright light. Any foreign spots or stripes indicate a defect in the matrix or plume.
⚠️ Warning: Prolonged display of static bright images (especially white) on the OLED-The screens may be burning, but for IPS-Redmi Note 8 Matrix – Short-Term Test is Safe.
Checking the Touchpanel sensor is critical after changing the glass or falling. As mentioned earlier, you need to swipe your finger across all squares. If the line is interrupted or changes color, then the sensor is not working in this area. Also check the multi-touch by touching the screen with two fingers at the same time.
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Qualitative sensor calibration in the engineering menu can fix problems with phantom presses, but will not restore a physically broken digitizer.
Checking of sound system and microphones
Xiaomi's audio tract has several components, and you'll find items in the diagnostic menu to check the main speaker, the speaker, and the microphones, and users often complain that they're not hearing well.
To check the microphones, select the appropriate item (often several: the main one and the additional one for noise cancellation). Speak to the phone, and the system will record the sound and play it back, which allows you to assess the purity of the recording and the presence of wheezing.
If you hear a crackling or wheezing at maximum volume in the Speaker test, it may indicate moisture or wear on the speaker. In the engineering menu, you can also check the headphones if they are connected through the 3.5mm connector that the Redmi Note 8 has.
Testing of communication modules and sensors
A modern smartphone is a set of sensors. An accelerometer, a gyroscope, a light and proximity sensor are all checked in the CIT menu. For example, the Proximity test shows values in numbers. When you cover the top of the screen with your hand, the values should change dramatically (usually from 5.0 to 0.0).
If the proximity sensor doesn't work, the screen won't go out during the conversation, and you'll be able to push the extra buttons with your cheek. The engineering menu often has calibration of this sensor available, which solves the problem 90 percent of the time without going to the service.
Communication modules are checked through WLAN, Bluetooth and GPS. For the Redmi Note 8, it is important to check Wi-Fi at 2.4 and 5 GHz. If the phone does not see the 5 GHz network, it may be an antenna or software failure problem.
⚠️ Note: Do not change the values in the points related to IMEI or MAC-Resetting this data may make it impossible to connect to the operator's network.
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If the proximity sensor shows incorrect values, try to clean the dust from the protective glass at the top of the case, often the problem lies in the contamination.
Frequent Problems and Their Solutions in CIT
One of the common problems after changing the screen is a failed proximity sensor. Xiaomi's engineering menu has a calibration function. Find the Proximity sensor and follow the instructions on the screen (usually you need to close your hand to the top of the phone and press the calibration button).
Another problem is the color rendering that is "fooled": after resetting or updating MIUI, colors can become too pale or saturated. In the engineering menu, you can find color profile settings, but it is better to use the standard display settings in the regular menu.
If the tests show Failed errors, try restarting the device and retesting. Software failures are sometimes disguised as hardware malfunctions. If the error repeats after the reboot, it is likely that a replacement component is required.