@supercadad said in Double check code for large format please:
What does the T0; Select first tool do?
It selects a tool so that you have a valid target for setting temperatures etc. You can't print without a tool. Adding T0 to config.g means that a tool will be selected at startup. You can also add T0 to your start.g file. or to the slicer start code. Most slicers will also ensure a tool is selected before they set a temp, but users always seem to find a way to work around that and end up with an error from trying to extrude with no tool selected.