Checking the technical condition of a smartphone before buying or after repair is a critical step that is often ignored by ordinary users. In the devices of the Xiaomi brand for this purpose, there is a hidden system section known as the Engineering Menu or CIT (Customer Information Test), access to which allows you to conduct a deep diagnosis of all hardware modules without installing third-party software.
Many gadget owners are wondering how to check Xiaomi’s engineering menu to make sure the touchscreen, speakers, or proximity sensors work. This hidden interface is built into firmware in the factory and is available even on a locked bootloader. Using the standard diagnostic tools gives the most accurate results, since they are designed by the company’s engineers specifically to detect hardware failures.
In this article, we will detail how to log into the hidden section, describe the purpose of the basic tests and give recommendations for interpreting the results.You will learn how CIT mode differs from the usual Android engineering menu and what commands are relevant in 2026 on modern versions of MIUI and HyperOS.
⚠️ Note: Making changes to modem settings or sensor calibration without understanding the process can cause communication or camera to malfunction.Use Test only, avoiding Write or Calibration unless you are a professional wizard.
What is the engineering menu and CIT in Xiaomi smartphones
The engineering menu in the Android ecosystem is a set of tools for debugging the radio module and basic system parameters. CIT (Customer Information Test: This is a specialized diagnostic interface that allows you to consistently check every component of the device, from the vibrator to the vibrator. GPS-module.
The main difference between the standard Android engineering menu and CIT is the depth of access. If the first one is more often related to network settings and radio channel information, the second one is a full-fledged checklist of hardware tests, and when you run the check, the system will tell you what action to perform, such as touching the screen or making a sound.
This tool is especially useful when buying a device from hand, and only through CIT can you identify the “dead” areas of the touchscreen or broken microphones that are not visible in normal use of the interface, the hidden nature of the partition protects it from accidental activation by curious users.
Entry methods: codes and system settings
There are several proven methods of activating the diagnostic mode. The fastest and most common way is to use the diagnostic mode. USSD-This method works on most models, including Redmi and the other POCO, whatever the shell version.
To enter, you need to open a standard caller and enter the following sequence of characters:
##6484##If the code is entered correctly, the menu will open automatically immediately after the last character is entered, you do not need to press the call button. In some cases, especially on new versions of HyperOS, direct code entry can be blocked by the security system, then you should use an alternative way through the settings.
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If the ##6484## code doesn't work, try typing it into the Phone app without pressing the call button, and some models help by deleting the last digit and re-entering it.
An alternative login method requires you to go to the settings menu, which is convenient if the phone keyboard does not respond to the input of special characters or the layout is changed. The path may vary slightly depending on the firmware version, but the logic remains the same.
The following actions are to be taken:
- 📱 Go to your smartphone settings.
- 🔍 Select the item About phone (About phone).
- ⚡ Find the line The kernel version or version MIUI.
- 👆 Quickly click on this line. 5-7 successively.
After a series of taps, the test list will open, and it's important to understand that some global firmware versions may have limited access through settings, and code remains the only working option.
Diagnostics of the display and sensor (Touchscreen)
One of the most common problems users face is the incorrect operation of the touchscreen. In CIT mode, screen testing is carried out in several stages, allowing you to detect both broken pixels and loss of sensitivity in certain areas.
When you run the Touchpanel test, the screen turns white, and your task is to swipe your finger across the entire surface of the display, and the touching area is left with a colored trail, and if the line is interrupted or not drawn in some corner, it indicates a physical malfunction of the digitizer.
Then the system will test the multi-touch, and you'll have numbered dots on the screen that you need to press simultaneously or sequentially, and the sensor will respond to all the dots without delay, which is critical for comfortable printing and gaming.
☑️ Screen checklist
Also available in this section is a color test, which is consistently filled with red, green, blue and white, and carefully examine the matrix for foreign spots, yellowness or differences in shades around the edges, which is often found after poor repairs.
Audio system and microphone checks
The audio diagnostics in Xiaomi’s engineering menu separates software problems from hardware malfunctions of speakers, and the test is usually divided into the main speaker, talk speaker, and microphones.
When you activate the corresponding item, you'll hear a characteristic beep or melody. If the sound is distorted, wheezing or absent at all, the problem is most likely in the speaker or plume itself. For microphones, the system will record your voice and play it back to check the quality of the recording.
Modern smartphones have multiple noise reduction microphones, and you can check each one separately in the diagnostic menu, which helps you to identify when you're not listening to someone while you're recording a video.
| Component | What we check. | Normal reaction. |
|---|---|---|
| Receiver (Conversational) | The sound in the ear | Pure sound without wheezing |
| Speaker (Main) | High-profile/media | Loud, surround sound |
| Main Mic | Main microphone | Clear voice recording |
| Sub Mic | Noise suppression | Recording from the second microphone |
⚠️ Attention: When testing microphones in the room should be quiet, extraneous noises may be mistaken as a malfunction or, conversely, the quiet sound of a microphone working.
Testing of sensors and communication modules
A smartphone is a complex set of sensors that make it work autonomously, and you can check the accelerometer, the gyroscope, the light and proximity sensor on the engineering menu, and the latter often causes the screen to stay on the phone when it's talking.
To check the proximity sensor, you need to close the top of the screen with your palm. The indicator on the screen should change the value from 1.0 to 0.0 (or vice versa, depending on the version of the test). If there is no reaction, it is possible that the sensor is contaminated or peeled off when changing the glass.
The test deserves special attention. GPS And networks «GPS» You'll see a map and a list of visible satellites. 1-2 Outdoors, possibly damaged antenna, Wi-Fi and Bluetooth test to test the ability to scan the airspace.
What if the proximity sensor is not calibrated?
Vibration testing is also included in this unit, the motor must vibrate at different intensity, and the absence of vibration or "crack" indicates mechanical wear or break of contact.
Analysis of battery and charging system
Battery status is a key parameter for the used device, and you can see not only the current percentage of charge, but also the status of the charger connection, as well as the voltage at the terminals, on the CIT menu.
The Battery section displays the actual capacity (design capacity vs current capacity) and the number of recharge cycles (if the battery controller supports the transmission of this data).
It also checks the LED light (if it's in the model) and the response to the USB cable. The system should instantly detect the transition to charging mode. Delays or permanent reconnections indicate problems with the Type-C connector.
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The battery health in the engineering menu is the only reliable data that can be trusted. Apps from the Play Market often show values read from the system log rather than directly from the controller.
Pay attention to the battery temperature during the test. If the smartphone is at rest above 35-40 degrees, this may indicate a short circuit in the power supply or a malfunction of the charge controller.
Frequent errors and their decoding
When you pass a test, you may encounter error messages, and understanding the nature of the error will help you avoid panic, and often a "mistake" is just a requirement to perform an action you missed.
For example, the word "fail" in the test SIM-The card may mean that the card is not inserted at the moment, rather than that the slot is broken.The camera test may not start if an application using the lens is already running in the background.
System failures in memory test (RAM/ROM) are rare but critical. If the test reveals broken sectors in memory, operation of such a device is not recommended, as this leads to constant reboots and data loss.
- 🚫 Test Fail: Component not answered or answered incorrectly.Replacement or repair required.
- ⏳ Timeout: Exceeded time for user action.Try to pass the test faster.
- 🔌 Not Connected: The device is not connected (relevant for charging tests and USB).
It is important to distinguish between software glitches and other breakdowns. Rebooting the smartphone before starting a diagnosis helps to eliminate the influence of background processes on the test result.