What happened?
The MMU3 works with 5 filament positions (called “tools”), labeled 1 to 5 on the unit. It is possible to select a filament using G-code commands in the format T[number].
T0: Filament 1
T1: Filament 2
T2: Filament 3
T3: Filament 4
T4: Filament 5
Special Commands:
Tx: Lets the user select a filament position from the LCD menu
T?: Legacy G-code for Tx
The MMU3 only supports tool numbers T0 to T4. If you send a command outside this range (for example, T5), the printer will display an error because that tool does not exist.
How to fix it?
If you use a 3rd party software to control the MMU printer, make sure the number of extruders is set to 5, counting from T0 to T4.
In case you are using a 3rd party hardware solution allowing for more than 5 materials to be used, please use the corresponding 3rd party firmware for the device too.