Robot vacuum displays E3 or three beeps and stops; may announce 'side brush error'.

Safety first: Power the robot OFF before touching the brush.

• Remove the side brush: Turn the robot over. Use a screwdriver (if required) to remove the screw holding the Hoover side brush, then pull the brush off the shaft.
• Clean the hub and shaft: Remove hair, string, and debris from the brush hub and from around the motor shaft. Use tweezers for tight areas.
• Check the motor: With the brush removed, gently spin the motor shaft with your fingers. It should turn smoothly without grinding.
• Reinstall or replace brush: If the bristles are bent or worn, install a new Hoover side brush. Tighten the screw securely but do not overtighten.
• Test operation: Turn the robot ON and start a cleaning cycle. Watch the side brush to ensure it spins freely.
• If E3 returns: The side brush motor or gearbox is likely failing. Replace the side brush motor module following the service manual (remove bottom cover, disconnect motor harness, and swap module).