Robot mower shows E8 and stops; may occur randomly during operation without obvious obstruction.

Safety first: Turn OFF the mower and place it on a stable surface.

• Check bumper movement: Gently press the front bumper in and release. It should move freely and spring back without sticking.
• Remove debris: Inspect the gap between the bumper and chassis for grass, twigs, or stones. Clean thoroughly.
• Visual inspection: Look for cracks or deformation of the bumper that could cause constant activation of the collision sensor.
• Reboot: Turn the mower back ON and test. If E8 appears immediately without touching the bumper, the internal collision switch or sensor wiring may be faulty.
• Service: For internal bumper switch replacement, the top cover usually must be removed. If you are not comfortable opening the mower, contact a service technician.