What Does This Error Mean?

Error E4 on a Brother sewing machine means the thread sensor detected an issue — most often the upper thread snapped or ran out mid-stitch, or the thread was not routed through the upper thread sensor guide. Cut all thread, re-thread the machine from scratch following the threading diagram, and restart.

Affected Models

Brother SE700
Brother SE1900
Brother CS7000X
Brother NS2850D
All Brother computerised models with E4 error

Common Causes

Upper thread snapped during sewing
Upper thread spool ran out
Thread not routed through the upper thread sensor (last guide before the needle)
Thread tension too high causing thread to break under load
Lint buildup in the thread path interfering with the sensor reading

How to Fix It

Remove all thread and re-thread from scratch.

Cut and remove the upper thread completely. Turn the machine off and back on to clear the E4 error state. Re-thread the upper thread following the numbered threading diagram printed on your Brother machine, making sure the thread passes through every guide in order.
Pass thread through the upper thread sensor.

The upper thread sensor on computerised Brother models is usually a small guide or slot near the top of the machine, just before the thread goes down toward the needle. The thread must pass through this guide — if it is bypassed, the sensor reads no thread and triggers E4.
Check the spool and bobbin.

Confirm the thread spool is not empty and is seated correctly on the spool pin with the spool cap in place. Also check that the bobbin is wound evenly and placed in the bobbin case with the thread feeding correctly.
Reduce thread tension.

If the thread is breaking during sewing and causing E4, the tension may be set too high for the fabric and thread combination. Reduce the upper tension setting by 1–2 points and test on a scrap piece of the same fabric.
Clean the thread path of lint.

Use a soft brush to clean the thread guides, tension discs, and the area around the upper thread sensor. Lint caught in the tension discs can cause irregular thread feeding that the sensor interprets as a thread break. Brother recommends cleaning the tension area after every 8–10 hours of sewing.

When to Call a Professional

If Error E4 appears immediately on startup before any sewing begins, and re-threading does not clear it, the upper thread sensor itself may be dirty or faulty and need cleaning or replacement.