Robot announces E3 or shows E3 in the app; side brushes do not rotate or stop intermittently.

Safety first: Turn off the robot and flip it over on a soft surface to avoid scratching sensors.

Clean and inspect side brushes:

• Remove each side brush by unscrewing the retaining screw or pulling it off (depending on model).
• Cut away hair and threads from the base of the brush and around the motor shaft.
• Check that the plastic hub of the brush is not warped or cracked. A warped hub can drag on the bottom cover.
• Spin the motor shaft gently with your fingers; it should turn freely. If it feels stuck or gritty, debris may be inside the gearbox.

Reinstall and test:

• Reattach the side brushes firmly but do not overtighten the screws.
• Power on the robot and start a cleaning cycle. Observe whether the side brushes spin normally.

If the error persists: The side brush motor or gearbox may be damaged. Continued use can overload the main board. Replace the affected side brush motor module or contact a technician for diagnosis and replacement.