The hidden engineering menu in Xiaomi smartphones is a powerful tool for diagnosing and fine-tuning the system, which is often sought by advanced users. This is where CIT tests, which allow you to test the health of each sensor, screen or communication module without installing third-party software, are hidden. The developers left this section for factory testers, but its functionality is open to anyone who knows the right sequence of actions.
Logining to this section does not require root rights or unlocking the bootloader, which makes the procedure safe for the average user. However, it is worth noting that changing some parameters can lead to unstable operation of the device, so you need to experiment with caution. Below we will look at all known ways to activate hidden functions and understand what the main partitions are responsible for.
Note that the interface and availability of options may vary depending on the version of the MIUI shell or HyperOS. If one of the methods did not work on your model, for example, the Redmi Note or the Mi series, try the alternative option described below.
What is the Engineering Menu and Why You Need It
The main purpose of the hidden partition is to quickly diagnose hardware components immediately after assembly on the conveyor. Engineers use CIT (Customer Integration Test) to make sure that the microphone, speaker, camera and sensors work correctly before packaging.
In addition to diagnostics, you can also use settings that are usually hidden in the standard Android interface, which means you can check the signal level in real time, know the exact temperature of the battery, or change the display settings, which is especially useful when buying a used device, when you need to quickly check whether the screen or battery has changed.
⚠️ Warning: Changing the settings in the Radio or Network section may result in loss of communication or inability to connect to the mobile network.
It is important to distinguish between the normal settings menu and the engineering mode. Standard settings allow you to manage applications and appearance, while the engineering menu gives access to low-level modem and processor functions. Errors here can be critical, so it is recommended to study the purpose of each tab in advance.
Preparation of the smartphone before entering the diagnostic mode
Before you enter secret combinations, make sure the device is at least 30-40% charged.Although the codes themselves do not consume much power, running heavy tests such as checking the screen or calibrating the sensor can quickly drain the battery.
It is recommended to turn off flight mode and make sure that SIM-The card is set correctly if you plan to test the communication modules. GPS or mobile data, the presence of an active SIM card and network signal is a prerequisite.
☑️ Checking before diagnosis
Back up your important data if you plan to not just browse, but make changes. While logging into the menu through codes is safe, accidentally pressing the reset button inside the test mode can delete user data. Backup is your insurance against human error.
Basic codes for CIT login and engineering menu
The easiest and most reliable way to get into the hidden section is the use of special USSD-These combinations work on most modern Xiaomi, Redmi and other models. POCO, No matter the year of issue, enter the code and the transition should occur automatically.
Please note that some codes may not work on global firmware versions due to regional carrier restrictions or MIUI settings.
| Team team. | Description of function | Works on |
|---|---|---|
| ##64663## | CIT main menu (equipment tests) | All models. |
| ##4636## | Testing menu (phone info, battery) | Android / MIUI |
| ##3646633## | Engineer Mode (MediaTek processors) | Budgetary models |
| ##8255## | GTalk Service Monitor | Old versions |
If you don't open the menu with ##64663##, try entering it without pressing the call button. The system needs to recognize the sequence of characters. In rare cases, new versions of HyperOS may restrict access to CIT through the developer's settings.
What do I do if the codes don't work?
Detailed overview of CIT menu functions
Once you log in, you'll see a list of dozens of tests, each point is responsible for a specific node on your smartphone, like the Receiver test, which checks the speaker, and the Lcd test, which allows you to see broken pixels or check the uniformity of the backlight.
The Version section is particularly noteworthy, where you can see detailed information about the build, base station version and firmware compilation date, which is useful when comparing a device to the claimed specifications or when looking for information to flash.
- 📱 TouchPanel: check the multi-touch and screen sensitivity. Draw lines to make sure there are no tears.
- 🔊 Speaker and Receiver: Playing sounds of different frequencies to check the audio track.
- 📸 Camera: Sequential launch of front and main cameras with autofocus check.
- 📡 Sensor: checking the accelerometer, gyroscope, proximity sensor and illumination.
After passing the test, the system usually produces a Pass (successfully) or Fail (error). If you see Fail on a working device, try restarting the smartphone and repeating the procedure. False positives are possible if there is a protective film or contamination of the sensors.
💡
When you test the proximity sensor, close the top of the screen with your hand. If the value changes from 5.0 to 0.0, the sensor is in good working order.
Configure the radio module and network through Engineering Mode
MediaTek processors (code #3646633##) can access a deep setup of the radio part, where you can force the network modes to switch, for example, make the phone only work in 4G LTE or, conversely, leave only 2G to save charge in the area of poor reception.
Connectivity tab allows you to manage Wi-Fi, Bluetooth and GPS. You can see it. MAC-So, you can use the address, you can use the debugging, you can run the signal reception tests, and it's an indispensable tool for those who live on the edge of the tower coverage.
⚠️ Note: Do not change the settings in the section NVRAM. This storage holds unique calibration data from your modem, and if it's damaged, it'll cause you to lose it. IMEI and the inability to work in cellular networks.
Region switching is also available here, and changing region can help if your smartphone doesn't see the local carrier's frequency or if you're traveling, but after changing region, you may need to reboot the device completely to apply the settings.
Secrets of Android Testing Menu (4636)
Code ##4636## opens up the standard Android testing menu that is present on most devices, including Xiaomi, and here the information is presented in a more structured form, divided into tabs. This menu is less dangerous for beginners, since most features here are read-only.
In the Phone Information section, you can force the network type to be set. If you have 4G/3G constantly downloading, you can fix LTE Only. This often helps stabilize the Internet on your trips, although incoming calls may stop coming if VoLTE technology is not enabled.
The Usage tab shows detailed statistics on running processes and screen time. It's a great way to find a parasite application that quietly drains the battery in the background. The statistics here are updated in real time.
💡
Use the 4636 LTE Only menu to improve Internet stability in areas of unsuspected reception.
Possible problems and solutions
A common problem is that the menu opens, but all tests are not available (gray) or an error crashes, which may mean that the Settings or Phone app doesn't have the necessary permissions. Go to the application settings, find the system application and check the access permissions.
Some global firmware has system-level blocking of the engineering menu, so changing the region to India or China will help, and then the codes can work, and remember to bring the region back after diagnosis.
- 🔄 Reboot: Often solves the problem of testing freeze.
- 🚫 Antivirus: temporarily disable third-party protections, they can block system calls.
- 🔋 Energy saving: Turn off hard energy saving modes before the test.
If nothing works, your model may have specific protections, and it’s worth going to the dedicated forums where specific Redmi or Black Shark models are discussed.