How to open the engineering menu on Xiaomi Redmi Note 9 Pro: secret codes and features

Xiaomi Redmi Note 9 Pro is one of the most popular smartphones of the mid-range segment, but not all users know that under its “hood” hidden powerful tools for fine tuning. The Engineering Menu (or Engineer Mode) lets you test hardware, calibrate sensors, and in some cases even unlock hidden features not available in the standard interface. MIUI. However, working with this menu requires caution: improper actions can lead to malfunctions in the device or even to the loss of warranty.

In this article, we will discuss in detail how to safely access the engineering menu on the Redmi Note. 9 Pro (models) joyeuse/curtana), What secret codes are used to do this, and what you can configure inside, and we'll focus on the risks and the warnings to keep your smartphone from getting damaged. If you're willing to dive into a world of hidden possibilities, read on!

What is an Engineering Menu and Why You Need It

The Engineering Menu is a service interface designed to test and diagnose the hardware components of a smartphone.

• 🔧 Service centers for checking the operability of sensors, communication modules and display.
• 📡 Developers for debugging firmware and testing new functions.
• 🔍 Advanced users to unlock hidden options (for example, enabling VoLTE on unofficial firmware).

On Xiaomi Redmi Note 9 Pro, the engineering menu allows:

• 📱 Check the status of the battery (real capacity, number of charging cycles).
• 🎤 Test microphones, speakers and vibration output.
• 📶 Analyze the network signal (level) RSSI, tower-tower).
• 🔄 Calibrate sensors (gyroscope, accelerometer, compass).

⚠️ Attention: Changing the parameters in the engineering menu can disrupt the stability of the smartphone, for example, incorrect calibration of the proximity sensor will lead to spontaneous shutdown of the screen during calls.

It is important to understand that Xiaomi does not officially support users access to this menu, you perform all manipulations at your own risk. If the device is guaranteed, it is better to refrain from experimenting - the service center may refuse to repair, finding traces of interference.

How to log into the engineering menu on Redmi Note 9 Pro

There are several methods to open the engineering menu on the Redmi Note 9 Pro. USSD-But their effectiveness depends on the version. MIUI And regional firmware. Let's look at all the work options.

Method 1: Standard code for MIUI

On most Xiaomi devices with firmware MIUI (The following code is used including Redmi Note 9 Pro:

##4636##

After entering this code on the lock screen or in the Phone application, the "Testing" menu with tabs will open:

• 📊 Phone information (network, battery, usage data).
• 🔄 Battery statistics (discharge schedules, temperature).
• 📡 Usage statistics (app activity).
• 🔧 Wi-Fi settings (hidden connection settings).

If the code doesn’t work, try an alternative:

##36446337##

This menu provides access to engineering mode with advanced options including tests. GPS, Bluetooth and NFC (If the module is present in your model).

Method 2: Using the Phone app (for Chinese firmware)

On devices with the Chinese version MIUI (for example, MIUI China Stable: Standard codes may not work:

1. Open the Phone app.
2. Go to the keyboard tab.
3. Enter the sequence: ##4636## (no stars!).
4. Press the call button.

If the menu does not open, try using the application to enter engineering codes, for example, MTK Engineering Mode (available on Google Play) supports MediaTek chips that power the Redmi Note 9 Pro (Snapdragon processor). 720G non- MTK, But some functions can work).

Method 3: Through ADB (for advanced users)

If USSD-codes do not work, you can use debugging USB (ADB). This method requires a computer and installed Xiaomi drivers.

Instructions:

1. Turn on Developer Mode on your smartphone: go to Settings → About Phone → MIUI version and tap 7 times.
2. Return to Settings → Additional → For developers and activate Debugging over USB.
3. Connect your phone to your PC and execute the command:

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

Then, the Engineer Mode option will appear in the settings. Alternative command for direct start:

adb shell am start -n com.miui.engineermode/.EngineerMode

⚠️ Attention: Use ADB This can cause the Mi Account to be reset if the device is activated by the Xiaomi account binding!

What to do in the Redmi Note 9 Pro Engineering Menu

The engineering menu provides access to dozens of options, but most of them are for professionals. We will only look at useful and safe features that will not damage the device when used correctly.

1. Testing of hardware components

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

• 🔋 Battery: real capacity, voltage, temperature. If Battery Health is below 80 percent, it's time to change the battery.
• 📞 Communication module: signal strength (RSSI), ranges 4G/5G.
• 🎵 Audio: performance of microphones, speakers, connector 3.5 mm (if any).
• 📱 Sensors: calibration of a gyroscope, accelerometer, light sensor.

To run the test:

1. Select a category (e.g. Battery).
2. Press Start Test.
3. Follow the instructions on the screen (e.g., shake the phone for the accelerometer test).

Network and communication configuration

In the Telephony or Network section, you can:

• 📡 Manually select a network (useful if automatic search is not working).
• 🔄 Reset your mobile network settings (if the internet is missing).
• 📶 View information about the cell (LTE Band, PCI, RSRP).

Important: Modification of parameters LTE Band can cause network loss! If you're not sure, don't touch these settings.

Sensor calibration

If your Redmi Note 9 Pro doesn’t have a screen autorotation or gestures working correctly, you can recalibrate the sensors:

1. Go to Sensor Test.
2. Choose the Accelerometer or Gyroscope.
3. Put your phone on a flat surface and press Calibrate.

After calibration, restart the device, and if the problem persists, the sensor may be physically damaged.

💡

Before calibrating the sensors, make sure the phone is on a perfectly flat surface, and even a slight tilt will distort the results.

Risks and Warnings When Working with Engineering Menus

The engineering menu is not a toy. The wrong actions can lead to:

• 🔌 Network loss (if you change your Modem or Radio settings).
• 🔋 Quick discharge of the battery (when resetting the battery calibration).
• 📵 Non-functioning sensors (e.g., proximity sensor will stop turning off the screen during a call).
• 🚨 Hardware failure (in rare cases - failure of the module) NFC Bluetooth).

The most dangerous sections of the engineering menu:

• RF Test – changing the parameters of the radio module can permanently shut down the mobile network.
• Factory Reset – Some items perform a complete reset to factory settings without warning.
• Hardware Info → Write – Recording incorrect data in EEPROM will cause irreversible damage.

⚠️ Warning: If after changes to the engineering menu, the phone stopped turning on or lost the network, try resetting via Recovery (press Power). + Volume Up when the device is off, 80 percent of the time, it helps to get back up.

If you're not sure what you're doing, don't change the settings, use the engineering menu only for diagnostics. For most tasks (like turning on VoLTE), there are safer ways to do it, through settings. MIUI or special applications.

Frequent Mistakes and How to Avoid Them

Even experienced users sometimes make mistakes when working with the engineering menu, and here are the most common ones and ways to prevent them:

Change of radio module parameters (RF Test)

Many people are trying to manually adjust LTE Band to improve network reception:

• ❌ Error: Disabling all bands except one.
• ✅ Solution: If you lose your network, reset your settings via #4636## → "Phone information" → "Resetting network settings".

Calibration of the battery without necessity

The engineering menu has the option of Battery Calibration, but:

• ❌ Error: Start calibration on a dilapidated battery.
• ✅ Solution: Charge your phone to 100% before calibrating, then discharge to 0% and recharge. Only then use the Reset Battery Stats feature.

3. Testing audio at maximum volume

In the Audio Test section, you can check the speakers, but:

• ❌ Error: Prolonged playback of the test signal at full volume.
• ✅ Solution: Use headphones or turn down the volume before the test. Otherwise, you risk damaging the speaker.

If your phone is not working properly, try:

1. Reset the device.
2. Reset network settings (Settings) → SIM-maps and mobile networks → Resetting network settings).
3. Restore factory settings (if other methods did not help).

💡

Never change the settings in the Factory sections, NV backup EEPROM. This can cause irreversible damage to the firmware!

Alternatives to the Engineering Menu for Diagnostics

If you just need to check the health of your smartphone, don’t take risks with the engineering menu.

1.Inline MIUI tests

Redmi Note 9 Pro has a hidden diagnostic mode that runs like this:

1. Go to Settings. → The phone.
2. Slip 5 times on the MIUI version.
3. Enter the password 123456 (if requested).
4. The menu will open. CTS Test with basic tests.

Third-party annexes

To check sensors and hardware components suitable:

• 📱 CPU-Z — Shows detailed information about the processor, memory, battery.

3. Diagnostic mode via computer

With Xiaomi PC Suite or Mi Flash Tool can run diagnostics without risking damage to settings. Connect your phone to your PC and select Device Test option.

These methods are safer than the engineering menu and are suitable for most tasks. Use them if you are not sure of your actions.

FAQ: Answers to Frequent Questions