Troubleshooting
Service Instructions 867 - 04.0 - 10/2019 135
25.3 Errors in sewing process
8402-8405 Error Internal error • Software update
• Machine ID reset
• Replace control
8406 Error Checksum error • Software update
• Replace control
8501 Error Software protection • Always use the DA tool for
software updates
Error Possible causes Remedial action
Unthreading at seam
beginning
Needle thread tension is
too firm
Check needle thread tension
Thread breaking Needle thread and hook
thread have not been
threaded correctly
Check threading path
Needle is bent or sharp-
edged
Replace needle
Needle is not inserted
correctly into the needle
bar
Insert the needle correctly into
the needle bar
The thread used is
unsuitable
Use recommended thread
Thread tensions are too
tight for the thread used
Check thread tensions
Thread-guiding parts, such
as thread tube, thread
guide or thread take-up
disk, are sharp-edged
Check threading path
Throat plate, hook or
spread have been
damaged by the needle
Have parts reworked by qualified
specialists
Code Type Meaning Remedial action
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