Robot vacuum reports 'Error 4' / voice prompt 'Error 4: Bumper error' and stops, often after hitting an obstacle.

Safety first: Turn off the robot before manipulating the bumper.

• 1. Free the bumper:
  • Press the front bumper in and release it several times across its width.
  • It should move freely and spring back evenly.
• 2. Remove debris:
  • Inspect the gap between the bumper and the robot body.
  • Use a thin plastic card or compressed air to remove dust, hair, or small objects.
• 3. Visual inspection:
  • Check for cracks or deformation of the bumper that might cause binding.
• 4. Advanced check:
  • Remove the top cover and front bumper (several screws).
  • Locate the bumper switch board and ensure the connector is firmly seated.
  • Press each microswitch by hand and listen for a clear click.
• 5. Replacement:
  • If the bumper is physically damaged or switches do not click, replace the bumper assembly or bumper switch board.