Prusa Research MMU3 Manual Del Usuario página 140

PASO 25 Error code details (Part 1)
Later on, an MMU error screen will show up if something goes wrong during the
operation. See the example image; the first line describes briefly, what's the error
about.
prusa.io/04101
the exact issue, and how to fix it.
FI:0 = SuperFINDA sensor reading. FI:0 = no filament detected. FI:1 = it is
detecting a filament.
(Note the FINDA status reading on the LCD has a slight delay.)
FS:0 is the IR Filament Sensor reading. This is the sensor inside the chimney
on the extruder / print head.
F1 is the expected filament position. It means, the selector is in the first
position. 1>3 would mean, the selector is changing from the first to the third. F?
= position not yet set.
205° is the current nozzle temperature.
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10B. Configuración y Calibración MK3S+
is a web address, where you can view a detailed article about
Ensamblaje Original Prusa MMU3