Robot lawnmower shows E10 Sensor Error; the mower behaves erratically near boundaries and obstacles.

Safety first: Switch off the mower and remove the battery before working on the bumper assembly.

• Check bumper movement: Press the front bumper at several points. It should move freely and spring back evenly. If it sticks, clean grass and dirt from the bumper gap.
• Inspect springs and guides: Remove the front cover to access the bumper mechanism. Check that the springs are intact and guides are not cracked or bent.
• Test microswitches (advanced): Locate the bumper switches and manually press them while listening for a click. Use a multimeter to verify continuity when pressed.
• Check wiring: Follow the bumper harness back to the main PCB. Ensure connectors are secure and wires are not pinched.
• Replace faulty parts: If a switch does not click or test correctly, replace the NAC bumper switch set or the complete bumper sensor assembly.

Warning: Do not operate the mower with the bumper disabled; collision detection is essential for safe operation.