Knowledge Base

How Do I Install LeJOS on the LEGO® MINDSTORMS® EV3 Brick?

For CoderZ to work with LEGO® MINDSTORMS® EV3 You will need to install Lejos on your EV3 Brick.

Here are the instructions to set it up:

You will need:

  • A minimum 2GB MicroSD card (Standard Capacity, maximum of 16 GB).
  • An SD Card Reader, or adapter, to connect the SD card to your PC.
  • EV3 download cable: USB A to USB - B mini

Lejos installation:

  1. Download, from here, the Lejos image in ZIP format.
  2. Unzip the content of the image onto the MicroSD card.
  3. Ensure that the EV3 Brick is switched off and insert the MicroSD card into the Brick.
  4. Power on the Brick.
  5. Allow a few minutes for Lejos to install


  • With Lejos installed on the SD Card, your EV3 brick becomes dual boot. Removing the SD Card (while the brick is turned off) will allow you to boot with the original firmware and run EV3-G programs.
  • To abort a program on your brick,  press both the Center and Down buttons.
  • High Capacity cards (SDHC) are not recommended  

That's it!

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