LG K40 Drivers LM-X420 – USB, ADB, Windows 10 & Mac

There are many instances when we need to connect our LG K40 to the computer. A successful USB connection is established only after the proper installation of the USB driver.

The LG K40 drivers needed for different kinds of USB connections are MTP driver for file transfer, ADB interface driver for ADB mode or USB debugging and USB serial port driver for download mode or firmware update via LGUP flash tool.

Let’s download the LG K40 Windows 10 / Windows 7  driver and learn how to establish a successful USB connection between our K40 and the computer by installing it –

How to install LG K40 USB Driver – Windows 7 & 10

Download the Latest LG K40 Driver for Windows and Mac from the respective download links –

LG K40 Mobile Driver v 4.4.2 – Download the setup file and save on your computer


LG K40 Mac Driver v5.4 –




LG K40 Drivers

Run the LG Mobile driver setup file i.e “LGMobileDriver_WHQL_Ver_4.4.2” as shown above.



Click “Next” to proceed further.


Wait for the driver installation to complete.

LG K40 USB Driver is installed successfully. We’re ready to connect our K40 in MTP, ADB & Download Mode.


1. LG K40 MTP Driver – File Transfer Mode


There are different modes of USB connection such as Charging, File Transfer, Photo Transfer & MIDI Device.

To transfer files between the K40 and PC we need to use the File Transfer Mode. In this mode, we can share any file stored in Internal Storage or Micro SD card including photos and videos.

Use a Micro USB Data cable to connect your K40 to the computer.

Select “File Transfer” as shown above.

Wait for the MTP (Media Transfer Protocol) driver to install. After the successful driver installation, the LG K40 device is visible under “Portable Devices” in Device Manager.


The LG K40 device is visible. For file transfer, choose “Open device to view files”.

You can see the LG K40 Internal Storage & SD Card are visible. We are ready to share files between the K40 and the computer.


2. LG K40 ADB Driver – USB Debugging / ADB & Fastboot Mode

To connect our K40 to PC in ADB mode we need to install the LG Mobile ADB Interface Driver.

ADB Mode can be used to boot our K40 into fastboot mode for bootloader unlocking. It can also be used to partition an SD card. After partitioning we can move apps to SD card and set SD card as the default storage space on our K40.

Before connecting the phone to the computer, we need to turn on USB Debugging.

Open Settings and select the “General” Tab.  Scroll down and open “Developer Options”. If you’ve not enabled developer options on your K40 learn how to enable it.

In “Developer Options”, look for “USB Debugging” and turn it on.

Now connect your K40 to PC using a Micro USB Data cable.


Wait for the ADB Driver installation to complete.

The ADB driver is visible in the device manager as “LGE Mobile ADB Interface” under “Android Device”.


When prompted, accept the request to “Allow USB Debugging” by tapping “OK” as shown above.


Now, Let’s check if we have successfully established the ADB connection using the Minimal ADB & Fastboot Tool.

You can see the adb devices command shows LG K40 under the “List of devices attached”.  The model number of K40 is visible which is LMX420.

3. LG K40 USB Serial Port & USB Modem Driver – Download Mode / Firmware Update Mode

The Download Mode is used to flash LG K40 stock firmware. It can help you in recovering your bricked LG K40 back to the working state. You can also use this mode to upgrade or downgrade your LG K40 firmware.

To boot your K40 into download mode –

  • Power off your phone
  • Connect one end of a Micro USB data cable to your K40
  • Press the Volume UP key on your phone.
  • Keep the Volume Key pressed, and connect the other end of the Micro USB Cable to the computer.


Our K40 is now in the Download Mode.

Wait for the “LGE AndroidNet Modem” and “LGE AndroidNet USB Serial Port” driver installation.

You can check the installation status using the Device Manager on your computer.

Now, we’re ready to flash stock firmware on LG K40.


For any query or feedback, feel free to leave a comment below.





1 thought on “LG K40 Drivers LM-X420 – USB, ADB, Windows 10 & Mac

  1. I want to buy 2 LG K40 MetroPCS, and have them rooted, so I can change the LTE Bands! And the Network Bands when I want too. But I don’t have the know how. So I am willing to pay to have it done! If someone really knows what to do, please email me? mr.jacklong169@gmail.com

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