Bobbin Sensor Error / False Low Bobbin
Janome Sewing Machine
Severity: MinorWhat Does This Error Mean?
The bobbin sensor error means the machine thinks the bobbin is empty when it is not. The sensor may be dirty, the wrong bobbin type may be installed, or the sensor is malfunctioning. Clean the sensor area and use the correct bobbin.
Affected Models
- Janome MC9900
- Janome MC6700P
- Janome Skyline S5
- Janome machines with bobbin sensors
Common Causes
- Bobbin sensor dirty with lint
- Wrong bobbin type (must be transparent/translucent for optical sensor)
- Bobbin inserted incorrectly
- Sensor malfunction
- Using coloured thread that confuses the optical sensor
How to Fix It
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Clean the bobbin sensor area.
The sensor is in the bobbin housing. Clean with compressed air or the lint brush.
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Use the correct bobbin type — must be clear/translucent.
Janome bobbin sensors use light to detect thread level. Opaque bobbins block the light and trigger false warnings.
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Reinsert the bobbin.
Remove and reinsert, making sure it clicks into the correct position.
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If the sensor keeps giving false warnings: you can often disable it.
Check your manual — some models allow disabling the low-bobbin warning in settings.
Frequently Asked Questions
Why must the bobbin be transparent?
Janome uses an optical sensor that shines light through the bobbin. When thread runs low, more light passes through, triggering the warning. Opaque bobbins block all light, confusing the sensor.
Can I ignore the low bobbin warning?
Yes, for a while. The warning appears before the bobbin is completely empty. You usually have several more inches of sewing before it runs out.