Robot vacuum shows C5 and refuses to start; bumper error or collision sensor error is announced.

Safety: Turn off the robot before manipulating the bumper.

• Check bumper movement: Gently press the front bumper in and release. It should move freely and spring back evenly across its width.
• Remove debris: Look along the gap between the bumper and the body. Use compressed air or a thin plastic card to dislodge dust, hair, or small objects.
• Inspect for misalignment: If one side of the bumper feels stuck, gently pull it outward and check for bent plastic tabs or misaligned guides.
• Test again: Power on the robot and start a cleaning cycle. Lightly tap the bumper to ensure it registers collisions and moves freely.
• Internal inspection (advanced): Remove the top cover or front shell (depending on model) to access the bumper sensor board and springs. Verify that the bumper microswitches or optical interrupters are not broken and that the wiring harness is secure.
• Replace if necessary: If the bumper cannot move freely or the sensors are damaged, replace the front bumper assembly or bumper sensor board with a Dreame-compatible part.