How to enter the engineering menu on Xiaomi Mi Max 3: secret codes and features

Xiaomi Mi Max 3 is the flagship phablet of 2018 with Qualcomm Snapdragon 636 or MediaTek Helio P60 processor (depending on the region), which is still popular thanks to the large screen and the possibility of deep customization. One of the most useful but hidden from the user features is the engineering menu - a tool for diagnosing, testing hardware components and fine-tuning network settings.

Entering this menu gives you access to GSM/CDMA/LTE tests, sensor calibration, battery checks, and even IMEI changes (on some firmware), but doing the wrong thing can lead to loss of warranty, communication module failures, or complete device buildup. In this guide, we will take a look at all the safe ways to log in, explain which settings can be changed without risk, and which ones should be abandoned.

What is an Engineering Menu and Why You Need It

Engineer Mode or Service Menu is a hidden section of Android designed to:

  • 🔧 Diagnostics of hardware components: checking the operation of the display, speakers, microphone, accelerometer and other sensors.
  • 📶 Network testing: signal strength analysis, selection of preferred connection type (2G/3G/4G), manual connection to base stations.
  • 🔋 Battery monitoring: checking the actual capacity, number of charging cycles, temperature.
  • 🛠️ Sensor calibrations: setting up a gyroscope, compass, proximity sensor (for example, to work correctly during calls).

On the Mi Max 3, the engineering menu is especially useful for:

  • 📱 Recovery IMEI After a failed firmware (only for versions with MediaTek).
  • 🔄 Forced switching between SIM-If the device does not see the network.
  • 🎯 Optimizing Internet Speed by Manually Selecting Frequency LTE.

⚠️ Note: Changing the parameters in the BandMode section (frequency selection) can lead to loss of communication if you do not know the ranges supported by your operator. For example, disabling the Band 20 (800 MHz) will make it impossible to work on the network. Tele2 or Iota in some regions.

How to find out the processor Xiaomi Mi Max 3

How you log in to the engineering menu depends on your device's chipset, and there were two types of processors installed on the Mi Max 3:

  1. Qualcomm Snapdragon 636 - most global versions (model code M1804E4A).
  2. MediaTek Helio P60 – some regional modifications (for example, for China, code M1804E4T).

To determine the processor:

  1. Open the Settings app → About the phone → General information.
  2. Find the line CPU model or Hardware.
  3. Alternatively, use the CPU-Z app (available in the Play Market).
📊 What is the processor of your Xiaomi Mi Max 3?
Qualcomm Snapdragon 636
MediaTek Helio P60
I don't know how to check.
Other

If your device is on MediaTek, you will have access to the extended MTK Engineer Mode menu with the ability to edit IMEI and deep modem customization. For Qualcomm, the functionality is limited to diagnostics and tests.

How to enter the engineering menu on Qualcomm-version

For devices with Snapdragon 636, there are two proven methods:

Method 1: Code for entering through the keyboard

The easiest way is to enter a secret code in the phone application:

  1. Open the standard phone application.
  2. Go to the keyboard tab.
  3. Enter the combination: ##4636###.
  4. On the screen will appear the Testing menu with tabs Information about the phone, Battery use, etc.

Battery charge of at least 30%|Disabled. VPN proxy|Backup of important data is made|The device is not connected to the PC-->

On this menu you can:

  • 📊 View information about the network (Signal Strength).
  • 🔄 Forced to switch between types of connections (Phone Information tab).
  • 🔋 See the actual state of the battery (Battery Information tab).

Method 2: Use of ADB (for extended access)

If the standard code doesn’t work (for example, due to customized firmware), you can use ADB:

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

For this:

  1. Enable USB Debugging in Settings → About Phone → MIUI version (click 7 times on the line).
  2. Connect the phone to the PC and execute the command above.

⚠️ Attention: On some firmware MIUI 12+ access ADB In this case, only the flashing on custom software (for example, LineageOS) will help).

Entrance to the engineering menu on MediaTek-version (Helio P60)

Devices with MediaTek Helio P60 have a more advanced engineering menu, but also a higher risk of "bricking".

Method 1: Standard MTK code

Enter in the phone keyboard:

##36446337##

After entering, the EngineerMode (MTK) menu will open with tabs:

  • 📡 Telephony - modem settings, SIM-maps, networks.
  • 🔧 Hardware Testing – Testing of hardware components.
  • 📊 Log and Debugging - Error logs.

Method 2: MTK Engineer Mode application

If the code doesn’t work, download the official MTK Engineer Mode app from the Play Market:

  1. Install and open the application.
  2. Select MTK Settings.
  3. Press Telephony to access network settings.
What to do if the menu does not open?
If nothing happens after entering the code, check: 1. Are ad blocking applications (such as AdGuard) that can intercept disabled? USSD-2. Is there a custom firmware installed with remote system utilities. 3. Try entering the code through the Google Phone app (if installed).

FunctionQualcommMediaTek
Display test❌ No.✅ Hardware Testing → LCD
Editing by IMEI❌ No.✅ Telephony → SIM1/SIM2 → IMEI
Manual selection of the network✅ Phone Information → Set preferred network type✅ Telephony → Network Select
Sensor calibration❌ No.✅ Hardware Testing → Sensor

What settings can be changed without risk

Not all of the options in the engineering menu are safe to edit.

  • 🔍 Tests of hardware components: checking the camera, speakers, vibration (partition Hardware Testing on the computer). MTK).
  • 📶 Network monitoring: viewing signal level, cell information (Phone Information tab on Qualcomm).
  • 🔋 Battery check: analysis of capacity, temperature, charging cycles.

What you can't touch without experience:

  • ⚠️ BandMode (frequency selection) – can cause network loss.
  • ⚠️ IMEI — Change will result in a blockage SIM-map.
  • ⚠️ NV Data – responsible for modem operation, errors lead to “bricking".

💡

Before any changes, take a picture of the current settings in the engineering menu, which will help you get it back if something goes wrong.

Frequent Mistakes and How to Avoid Them

Even experienced users sometimes make mistakes when working with the engineering menu.

1. lost network after BandMode change

If you manually shut down the frequencies used by your carrier, the phone will stop catching the network.

  1. Get back to BandMode.
  2. Select Auto or manually turn on all frequencies.
  3. Reset the device.

2.Reset IMEI on MediaTek

If, after editing, IMEI phone stopped seeing SIM-map:

  • Try to restore the original IMEI (usually listed on the box or under the battery).
  • Use the Maui META utility to flash the modem (PC required).

💡

On Xiaomi Mi Max 3 with Qualcomm, editing IMEI is impossible through the engineering menu - this is chipset protection. On MediaTek, this is possible, but it is fraught with locking the device by the operator.

3. Hanging in sensor testing

If the phone freezes during the Sensor test:

  • Wait for the battery to discharge (if the device does not respond).
  • Press Power + Volume up for 10 seconds for a forced reboot.
Can I unlock the bootloader through the engineering menu?
No, the engineering menu doesn't involve unlocking the bootloader, but you use the official Mi Unlock Tool and you link the Mi Account to the device, and the engineering menu is for diagnostics and testing only.
Why does nothing happen after the code is entered?
Possible reasons: Installed custom firmware without system utilities. USSD-Conflict with ad-blocking apps (disable them) Solution: try entering code through the Google Phone app or use ADB.
How to reset the settings of the engineering menu to the factory?
If you have changed the settings and want to get it back: On MediaTek: in the EngineerMode menu, select Restore Defaults. On Qualcomm: reset via Settings → System → Reset (does not affect user data).
Can you improve network reception through the engineering menu?
Yes, but with reservations: On Qualcomm, you can manually select a network type (for example, force LTE Only to be enabled), but this does not always improve the signal. On MediaTek, in the Telephony → Network Select section, you can select a specific base station, but this is a temporary solution. For stable improvement, it is better to use an external antenna or change the operator.
Is it safe to use the engineering menu on custom firmware?
On informal firmware (e.g. LineageOS, Pixel Experience), the engineering menu may not work properly or at all. Risks: Some commands may cause kernel errors. Sensor tests may show incorrect values. Recommendation: use only on stock MIUI or firmware based on official builds.