SATO FX3-LX Operator's Manual page 468

Cause and Countermeasure
Cause (3)
The media sensor type is incorrect.
Countermeasure (3)
Set the media sensor type which is compatible with the media you use.
Media Sensor Type
Cause (4)
The media sensor level is incorrect.
Countermeasure (4)
Adjust the media sensor level.
Calibrate
Contact your SATO technical support center if the error cannot be resolved.
Contact Information for When You Are in Trouble
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