Robot reports E5 and stops; it may be stuck near a drop or edge, or refuses to move forward.

Safety first: Turn off the robot and remove it from the dock.

• Locate cliff sensors: These are usually small infrared windows on the underside front edge of the robot.
• Clean sensors: Use a soft, dry microfiber cloth to gently wipe each sensor window. For stubborn dirt, lightly dampen the cloth with water (no chemicals) and dry immediately.
• Check environment: Very dark or reflective floors near stairs can confuse sensors. Test the robot on a lighter, non-reflective surface.
• Reset and test: Power the robot back on and start a cleaning cycle away from stairs.
• If E5 persists: The Cliff Sensor Array may be faulty or disconnected. Advanced users can remove the bottom cover, verify the sensor harness is firmly connected to the main PCB, and replace the sensor module if needed.