Robot vacuum reports E4 and stops, often after bumping into furniture.

Safety first: Power OFF the robot.

• Check bumper movement: Gently press the front bumper in and release. It should move freely and spring back evenly across the entire front.
• Remove obstructions: Inspect the gap between the bumper and the body for lodged debris (toys, cables, dirt). Use a thin plastic card or compressed air to clear the gap.
• Clean bumper sensors: If your Ultenic model uses infrared bumper sensors, wipe the sensor windows behind the bumper with a microfiber cloth.
• Tap to release: Lightly tap along the bumper to free any stuck internal switches.
• Test operation: Turn the robot back ON and start a cleaning cycle in an open area.
• If E4 remains: The bumper switch assembly or its wiring may be damaged. This requires removing the top cover, disconnecting the bumper harness, and replacing the bumper sensor module.