Bosch Washing Machine Error Code E21 — Low Drum Rotation Speed
What this means
Error E21 indicates the drum motor cannot maintain proper rotation speed. Common causes include worn carbon brushes on the motor, a broken or stretched drive belt, an obstruction inside the drum, or a failing motor control module. The washer may attempt to restart several times before displaying this code.
Alternate codes: F21
Step-by-step fix
4 stepsCheck for obstructions
Try to rotate the drum by hand. If it won't move or moves unevenly, an object like a coin or underwire may be jammed between the drum and tub.
Remove the sump hose or check the drain filter for trapped items.
Inspect the drive belt
Remove the rear panel and check the belt for wear, stretching, or breakage. A loose belt will slip and reduce drum speed.
The belt should be taut with only slight deflection when pressed.
Test the motor brushes
If your model has carbon brushes, inspect them for wear. Brushes shorter than 1 cm need replacement.
Worn brushes are the most common cause of E21 on older Bosch washers.
Test the motor windings
Use a multimeter to check the motor windings for continuity. No continuity means the motor needs replacement.
When to call a professional
If the motor or motor control module needs replacement, or if you cannot identify the obstruction.
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
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