Xiaomi smartphones are famous for their functionality and openness to advanced users, which is especially true for the Redmi Note 9 Pro. One of the key tools for diagnosis and deep tuning is the hidden partition of the system, often called the engineering menu or the “engineering” of the device. CIT-Access to it allows gadget owners to independently verify hardware components without using sophisticated computer software.
Unlike standard Android settings, this interface provides access to low-level features of the device, where you can run a vibration test, check the microphones, assess the accuracy of the accelerometer or even see the detailed status of the battery. For owners of the Redmi Note 9 Pro is an indispensable tool when buying a used device or when you experience strange malfunctions in the phone.
However, it is worth noting that interference with system settings requires caution, that changing critical settings incorrectly can lead to malfunctioning of the device. In this article, we will discuss in detail the safe ways of entering, consider the basic functions of the diagnostic menu and answer frequent questions of users.
What is hidden engineering interface Redmi Note 9 Pro
The MIUI shell engineering menu is a set of diagnostic tools built into factory testing. On the Redmi Note 9 Pro, this section is often referred to as the CIT (Customer Integrated Test), and its main purpose is to allow the engineer on the assembly line to quickly make sure that all the phone modules are working correctly before packaging.
User access to these features is a huge opportunity, for example, you can find out the actual wear of the battery, check for broken pixels on the screen or check the accuracy of the proximity sensor, Dianostic codes allow you to run these tests instantly, bypassing long chains of settings.
⚠️ Note: There are sections in the engineering menu that can cause software failure to change the parameters, and do not change the values in the sections that you do not know the purpose of, especially those that relate to the calibration of the sensor or radio module.
It is important to distinguish between the usual settings menu and the hidden engineering section. The first is for everyday use, the second is for maintenance. The Redmi Note 9 Pro features a state-of-the-art Snapdragon processor, and its diagnostic module is tightly integrated with hardware, making the check very accurate.
Preparation of the device for diagnosis
Before you start testing, you need to perform a number of preparatory steps, which will help to avoid false readings of sensors or interrupt the verification process, first of all make sure that the battery charge is at least 30-40%.
It's also recommended that you close all background applications, which will free up RAM and CPU time for diagnostic utilities. SIM-Cards or mobile internet, make sure the cards are inserted correctly and have an active balance.
☑️ Preparation of Redmi Note 9 Pro for tests
When testing multi-touch or calibrating the sensor, even drops of fat or water can distort the results. Wash the Redmi Note 9 Pro display with soft cloth before starting treatments.
Methods of entry through code combinations
The fastest and most proven way to get into the hidden section is the use of special USSD-They work at the system level and do not require any additional software installation. For Xiaomi and Redmi, there are several universal combinations that should work on the Note 9 Pro.
Open the standard Phone app and enter dial mode. Enter the following character sequence:
##6484##Once you enter the last character *, the phone will automatically go to the test menu. You don't need to press the call button. If the code doesn't work, try the alternative:
##4636##This code often leads to a menu of phone and status information, but on some versions of MIUI it can also open advanced testing settings. Successful login depends on the firmware version and the region for which the device is released.
It’s worth noting that codes may not work if you have custom firmware installed or if system files have been modified by root rights. In the stock version of MIUI, these combinations are active by default.
Entry through standard system settings
If the code set doesn't work for some reason, you can use the built-in search engine. The MIUI shell has a powerful search engine that indexes hidden menu items. Click on the search icon in the Tools folder or in the top settings menu.
Type the word "Test" or "CIT" into the search bar. The system should suggest "Test" or "Test device." Clicking on it will take you to the same menu as when you enter the code, which is a convenient way if you're afraid of getting the numbers wrong.
An alternative route is through the About Phone menu. Find the MIUI version and quickly click on it 7-10 times. Although this action usually activates the developer mode, in some firmware modifications, it can open access to additional logs or tests.
⚠️ Note: If the search does not find the “Testing” item, it is possible that your carrier or distributor has blocked access to these features in the software.
Sometimes you can find a sign-in shortcut in the Tools folder called "Verification" or "Cit." If you accidentally delete this application, you can only restore it by resetting settings or flashing it, so be careful with system shortcuts.
Overview of the main functions and tests of CIT
Once you log in, you'll see a list of dozens of items, each one of which is responsible for checking a particular Redmi Note 9 Pro module, and navigation is done by touching the screen, and then you'll see what's most useful to the average user.
The table below shows the basic test codes and their description, which you will find in the menu:
| Name of the test | Function | What we check. |
|---|---|---|
| Version | Information | CIT version, model, serial number |
| Touchpanel | Sensor | Touch accuracy, multi-touch |
| Receiver | Dynamician | The work of the conversational speaker |
| Vibrator | Vibration. | Vibrator performance |
| Front Camera | Camera. | The work of the front camera |
The Touchpanel test is particularly important, because when you start it, the screen turns color, and you have to swipe across all the boundaries, the lines have to light up green, and it reveals the dead zones of the sensor that are not visible in normal use.
What to do if the test is not passed?
Also useful is the Charger test, which shows the current charging status, voltage and type of power source connected, which helps to understand why the phone might charge slowly or not see the charger.
Screen and sensor diagnostics
The screen is one of the most vulnerable components of the Redmi Note 9 Pro. There are several tests on the engineering menu to test it. In addition to the multi-touch, there is a color bar, which displays monochrome images of different colors, which helps to find broken pixels or uneven backlights.
To check the sensor, select Touchpanel, and you'll be asked to draw lines along the circuit of the screen, and it's important that if the line is interrupted or doesn't light up in a certain place, it indicates physical damage to the digitizer or plume.
Often users complain of "phantom" clicks, a test in the engineering menu helps determine whether it is a software glitch or a hardware problem, if there are no presses in the diagnostic mode, and there are presses in the system, the problem is in the software or application conflict.
Verification of communication and wireless modules
Xiaomi's communication module is tested separately, and you can find items on the menu that are related to the SIM-The check shows whether the phone sees the card, what signal level and whether it is registered in the network.
There are also separate sections for Wi-Fi and Bluetooth testing, which allow you to search for networks or check data transfers, which is especially true if you have problems connecting to a router or wireless headphones.
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When testing GPS, it is better to go out into the open, and inside buildings, the signal may be too weak to correctly determine the coordinates, which will lead to a false test error.
If the communication test shows an error, try extracting and repainting. SIM-It's also worth checking if the contacts in the tray have oxidized, and in some cases, resetting the network settings helps, but it's already done outside the engineering menu.
Frequent problems and their solution
Redmi Note 9 Pro users sometimes experience a situation where menu logins are blocked or tests give out errors for no apparent reason, often due to access rights or damage to system files.
One of the common problems is that you can’t complete the test, and the Pass button may be inactive, so make sure you do all the things required by the test (e.g., close all the test application windows).
⚠️ Warning: Do not try to force the testing process to close through Task Manager.This may cause the system to freeze and require a restart.
If you have updated your firmware and the codes are no longer working, it is possible that the new version of MIUI has a changed security structure, and in such cases, it is recommended to use third-party applications from the Play Market, such as "Device Info HW" or "Phone Info SAM", which can read some of this information.
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The engineering menu is a powerful diagnostic tool, but it is not designed for the permanent use of ordinary users.