False 'bobbin empty' or 'upper thread missing' alerts can bring sewing to a halt. In this guide, based on Bernina Jeff’s video, learn how to identify, clean, and temporarily disable faulty sensors on your Bernina B770 so you can keep stitching while waiting for a service visit.
Table of Contents
Tired of Nuisance Errors? A Quick Guide for Bernina Users
When your Bernina suddenly stops mid-seam with a flashing “bobbin empty” message, yet you can see thread on both spools, you’re facing what Jeff calls a “nuisance error.” These can come from dust blocking a sensor or a chip reading issue.
Jeff begins by emphasizing a simple truth: you don’t have to run to the shop every time this message appears. His demo machine, a Bernina B770 Quilter’s Edition PLUS, behaves perfectly once the sensors are cleaned and adjusted.
Diagnosing the False Bobbin Error
Running the Test: When the Machine Cries Wolf
To showcase the issue, Jeff starts sewing normally. Midway through, the Bernina halts and flashes a bobbin warning.
Opening the case reveals a completely full bobbin. The machine just guessed wrong—confirming a false reading.
The First Fix: Cleaning Your Bobbin Sensor
Dust and stray thread fibers build up around the tiny “frog eyes” of the sensor near the bobbin. A few short swipes with a Q-tip or micro cleaning swab often restore proper function.
Avoid anything sharp that might scratch the optics.
Many sewists who left comments echoed this: wiping the bobbin door area solved their problem instantly. One viewer even found a single fuzz strand blocking the light path.
In case you’re switching between quilting and embroidery work, the same prevention mindset used when maintaining your hoop systems—such as bernina magnetic hoops—applies just as well to these sensors.
How to Temporarily Disable the Bobbin Sensor
If cleaning doesn’t help, Jeff’s next option is to disable the machine’s lower thread sensor temporarily so you can keep working until you can visit a dealer.
Navigating to the Sensor Settings Menu
On the home screen, tap the gear icon. This opens the settings menu.
From there, the eyeball icon leads to the sensors page, where upper and lower monitors appear.
Turning Off the Lower Thread Monitor
Tap the bobbin (lower) sensor icon to switch it off.
Exit the menu. The display briefly confirms the action. Now, sew again—the false message disappears, and the stitches continue normally.
If you’re practicing on paper templates or material prep rather than fabric, the freedom from interruptions feels liberating—a bit like using innovative accessories such as dime snap hoop monster bernina to streamline embroidery tasks.
Confirming the Fix
The video clearly shows smooth sewing right after the change. Jeff also points out that if your bobbin’s reflective marks (“mirrors”) are intact, the issue likely isn’t the bobbin itself.
Troubleshooting the Upper Thread Sensor
Identifying an Upper Thread Sensor Error
Next, Jeff unthreads the needle entirely. Unsurprisingly, the machine quickly displays “no upper thread.”
If you’ve already turned off the bottom sensor, this upper sensor still halts operation whenever it loses tension feedback.
Disabling the Upper Thread Monitor
Head back into the same “eyeball” menu and toggle off the upper thread sensor.
With both sensors inactive, you gain uninterrupted control for specific projects—such as perforating paper or sewing templates without thread.
While this bypass works, Jeff reminds viewers it’s only a workaround. Viewers chimed in that even after service appointments, persistent false upper-thread alerts sometimes crept back, so this technique remains a handy emergency fix.
> From the comments: Some sewists mentioned similar issues on other models—like the 440 or 880+—and appreciated that the same logic applies. When in doubt, always confirm procedures using your machine’s manual or support network.
For complex embroidery, ensuring your sensors function correctly helps when using precision positioning equipment like magnetic embroidery hoops for bernina or even cross-brand systems such as magnetic hoops for embroidery machines, which rely on exact fabric placement.
Sewing Without Limits (and Sensors)
Even though the Bernina continues stitching happily when both sensors are off, this freedom comes with responsibility. You’ll need to visually check your top and bottom threads to avoid running out mid-project.
In the comment section, Jeff confirmed this directly: once sensors are off, the machine won’t stop automatically—you must monitor it yourself.
Why This is a Temporary Solution
Jeff compares this fix to driving a car with the “check engine” light covered by tape—it gets you home, but it’s not a long-term answer. Use it to finish urgent sewing, but schedule proper service soon.
A good analogy also exists in embroidery framing: when you use add-on tools like bernina snap hoop or magnetic hoop for bernina, they simplify workflow but still require alignment practice before continuous use.
The Importance of Professional Service
When you bring your Bernina in, carry the same fabric, threads, and project pieces that triggered the error. That helps technicians duplicate the fault accurately. Document your temporary sensor settings (for example, both set to “OFF”) before they inspect the unit.
How to Help Your Technician Diagnose the Problem
Take a brief note of when the errors occur—during slow stitching, embroidery, or free-motion quilting. It’s just like noting when your car squeaks: details guide the fix.
And if your sensor errors started after long embroidery sessions, consider whether vibration or magnet exposure from other accessories—like magnetic embroidery hoop attachments—could be contributing factors.
Helpful Gadgets and a Special Offer
Accessorize Your Bernina
Jeff wraps up by showing a few of his clever 3D printed add-ons: holders for oil bottles, tweezers, plate covers, and presser feet.
Many commenters mentioned printing their own or buying them directly from his online shop.
These little helpers might not stop a bobbin error, but they certainly make routine maintenance more organized. Similar functional upgrades exist for embroidery setups, including precision accessories such as dime magnetic hoop and magnetic embroidery hoops. Each serves the same goal—keeping your workspace efficient and frustration-free.
A Free Gift from Bernina Jeff
As a sweetener, the first 42 orders after the video’s release come with a free sample of Orvus quilt soap—a gentle cleanser ideal for delicate projects.
It’s a small gesture that celebrates loyal followers helping one another—and a reminder that solid maintenance is the best embroidery accessory you can invest in.
From the comments: Viewers across models shared relief: “Problem solved!” and “You saved me a trip to the dealer!” A few still dealing with persistent errors plan to have their machines examined professionally, a sign that Jeff’s balanced approach (DIY first, dealer later) resonates.
By combining sensible cleaning, quick setting changes, and mindful follow-up, you can stay productive without letting error codes rule your creative time. When your Bernina says “no thread,” you’ll know exactly what it’s really trying to tell you.