Engineering menu on Xiaomi Redmi 9: how to go and what you can configure

Xiaomi Redmi 9 smartphones hide a powerful tool for fine-tuning under the hood, the engineering menu, which is designed to test hardware components, calibrate sensors and diagnose malfunctions, but access to it is blocked by default. Why? Because careless changes in parameters can lead to malfunctions in the device or even to its "bricking".

In this article, we will take a look at all the working ways to log into the engineering menu on Redmi 9 (including the Redmi 9A/9C/9T modifications), explain what features are available to the average user, and warn against dangerous experiments, learn how to use the hidden features of the phone without risk, and what to do if after changes the device began to work incorrectly.

Engineer Mode or Service Menu is a hidden partition of Android that manufacturers leave for internal testing and debugging, which focuses on low-level settings that are not available in the standard MIUI.

📡 Check the antennas' operation (LTE, Wi-Fi, Bluetooth, GPS) network signal
🔋 Calibrate the battery and analyze its wear
🎤 Set up microphone and speakers, eliminate noise
📱 Test sensors (gyroscope, accelerometer, proximity sensor)
🔧 Make changes to the firmware (for experienced users)

However, most of the parameters in the engineering menu are not detailed and are intended for service center specialists.

⚡ Network loss or communication impairment
🔇 Disappearance of sound in speakers
📉 Accelerated battery discharge
🚨 Complete inoperability of the phone ("brick")

⚠️ Note: Changes to the engineering menu are not covered by Xiaomi warranty.If you are not sure about your actions, it is better to contact the service center.

The manufacturer has provided several secure methods of accessing the engineering menu, which do not require superuser rights (root), all of which run on standard MIUI firmware (versions 12-14) and do not violate the warranty.

Method 1: Through code USSD-team

The easiest method is to enter a special code in the phone application:

Open the standard phone application.
Go to the keyboard tab (to dial a number).
Enter the combination: ##4636##
Press the call button (green tube).

After that, the Testing menu will open with the main sections: Phone Information, Battery Use, Usage Statistics and Wi-Fi information.

Method 2: Through the Developer Settings

If USSD-code failed (for example, due to operator locking), try an alternative path:

Activate Developer Mode (click 7 times on "Version") MIUI" on the telephone")

Enable "Debugging by USB" in the developer settings

Connect your phone to a PC with ADB drivers installed

Adb shell am start -n com.android.settings/.DevelopmentSettings

-->

After completing these steps, the Engineering Menu will appear in the settings (may be called Service Menu or MTK Engineer Mode if the phone is on a MediaTek processor).

Way of entering	Root is required.	It's powered by Redmi 9.	Risk to the system
USSD-code ##4636##	❌ No.	✅ Yes.	⚠️ Low.
Developer Settings + ADB	❌ No.	✅ Yes.	⚠️ Medium.
Apps from the Play Market (MTK Engineering)	❌ No.	⚠️ Partially.	❌ High-pitched
Manual input via adb shell	✅ Yes.	✅ Yes.	❌ critical

USSD-code|Developer settings|App from Play Market|Never tried.-->

Alternative methods (for experienced users)

If the standard methods don’t work, you can use advanced methods, but they require caution, and these options are suitable for the Redmi 9 models on the MediaTek Helio G35/G80 processors.

Method 1: Application of MTK Engineering Mode

For phones on MediaTek chipsets, Google Play has the official MTK Engineering Mode app:

Download and install the application (developer – MediaTek Inc.).
Start it and select MTK Settings.
Enter the password: 1234 (by default).

The app will provide access to advanced configurations of the communication module, battery and sensors, but not all functions will work without superuser rights.

Method 2: Through ADB (for PC)

If you have a computer, you can use Android Debug Bridge (ADB):

adb shell


su




setenforce 0




am start -n com.mediatek.engineermode/.EngineerMode

This command temporarily disables SELinux protection and triggers the engineering menu.Warning: Once the phone is restarted, the protection will recover, but the menu changes may persist!

⚠️ Attention: Use ADB With superuser rights (su) requires an unlocked bootloader and root rights.This voids the warranty and increases the risk of failure.

💡

Before using ADB, back up your data via adb backup or in your phone settings (System → Backup).

The engineering menu on Redmi 9 is divided into several tabs, and let’s look at the most useful and safe features that will not harm the device.

1. Verification of hardware components

In the Hardware Testing (or Equipment Testing) section, you can check:

📶 Network: Signal strength, type of connection (LTE/3G), IMEI
🔋 Battery: real capacity, temperature, voltage
🎧 Audio: test speakers, microphone, 3.5 mm connector
📱 Sensors: calibration of a gyroscope, accelerometer, compass

Network and communication configuration

The Telephony tab allows:

📡 Manually choose a communications operator (useful in roaming).
📶 Turn off certain ranges 4G (For example, the Band 20 to save charge).
📞 View the logs of the calls and SMS (diagnostic).

However, changing network settings (such as Network Mode) can cause communication to be lost. If the phone stops catching the network after the changes, reset the settings to factory:

##7465625##

Calibration of the battery

If the Redmi 9 battery is quickly discharged or shows an incorrect percentage, you can calibrate the following in the engineering menu:

Go to Battery Information.
Press Battery Calibration.
Connect the charger and wait for 100%.
Turn off the power and use the phone until it is completely discharged.
Repeat the charging-discharge cycle 2-3 times.

What happens if you reset the battery settings?

Battery Reset resets the wear and charge cycles, which can temporarily trick the system into showing 100% battery health, but the physical wear and tear will remain, and once it is reset, the phone may miscalculate the remaining charge, leading to a sudden shutdown at 20 to 30%.

Dangerous functions: what not to do

Some sections of the engineering menu are strongly discouraged from being modified without special knowledge, and here is a list of the riskiest actions:

🔧 Change of change IMEI: It's illegal and it's blocking the network. IMEI It can only be done through the service center.
📡 Disconnecting antennas: Deactivation RF Band may cut off the phone forever.
⚡ Overclocking of the processor: Increase in frequency CPU/GPU It causes overheating and shortening of the chipset’s life.
🗑️ Cleaning up the section EFS: This erases the critical data of the communication module, after which the phone turns into a “brick".

⚠️ Note: If you accidentally change your settings NV Data or Modem Settings, immediately reset via ##7465625##. Otherwise, you may need to flash it back.

Also avoid the titled sections:

Factory Reset (not to be confused with a regular reset in the settings!)
Flash or Firmware Update
Security Settings

💡

If you're not sure what the parameter is, don't change it. Most of the settings on the engineering menu have no reversible effect.

What to do if the phone breaks down after the change

If after interfering with the engineering menu Redmi 9 stopped turning on, does not catch the network or behaves unstable, act on the algorithm:

1. Mild discharge

Try restarting your phone in safe mode:

Press the power button before the menu appears.
Press and hold Turn Off → will be prompted to go to Safe Mode.
Confirm and wait for the download.

In Safe Mode, check if the problem persists. If not, it's the third-party app's fault.

2.Dumping through Recovery

If the phone is turned on but is not working correctly:

Turn off the device.
Press Volume Up + Power before the Mi logo appears.
Select Wipe Data → Wipe All Data (use volume buttons for navigation).
Confirm the reset and reset.

3. Flashing through Fastboot

If the phone is not turned on ("brick"), you will need firmware through the Mi Flash Tool:

Download the official firmware for Redmi 9 from en.miui.com

Install Qualcomm or MediaTek drivers (depending on the processor)

Unpack firmware in a folder without Cyrillic symbols

Run the Mi Flash Tool and connect the phone in Fastboot mode (Loud down + Power)

-->

After the firmware is erased, the phone will return to factory condition.

Frequently asked questions

Can I log into the engineering menu without entering codes?

Yes, on some MIUI firmware, the engineering menu is available through Settings → About Phone → All Specifications → Core (press 5 times on the Core).

Why doesn't it work? USSD-code ##4636##?

Possible reasons: Operator has blocked service codes (try another one) SIM-There's custom firmware installed that has removed the engineering menu. Phone on a Qualcomm processor -- try code #86583##.

How to reset the settings of the engineering menu to the factory?

There's no reset feature in the engineering menu itself. To return all settings to default, do: Recovery (Wipe Data). Or type in the code: ##7780## (soft reset). This won't affect user data, but it will return the system settings to the original settings.

Can I unlock the bootloader through the engineering menu?

No, the engineering menu does not provide access to unlock bootloader. You need to: Apply on the Xiaomi website (en.miui.com/unlock), wait 7-30 days (depending on the account), use the official utility Mi Unlock Tool.

Is there a risk of losing your warranty by simply going to the engineering menu?

No, simply logging into the engineering menu (without changing the parameters) is not a reason to withdraw the warranty, but if you: Changed the settings that caused the malfunction, Used root or custom software, damaged hardware components (for example, when testing speakers at maximum volume), then warranty repair may be rejected.