Robot mower shows E11 and stops; may coincide with erratic movement or inability to follow boundary wire.

Safety first: Turn OFF the mower and remove the battery before opening the housing.

Steps:

• 1. Check for interference: Ensure there are no high‑power cables, electric fences, or induction loops running close and parallel to the Yard Force boundary wire. Re‑route either if necessary.
• 2. Test on simple loop: Create a small test loop of boundary wire near the charging station and place the mower inside. If it still shows E11, the issue is likely in the mower.
• 3. Inspect boundary sensor: Open the mower and locate the boundary sensor coil (usually at the front). Check for physical damage or broken wires.
• 4. Check connections: Ensure the sensor connector is firmly attached to the main PCB. Look for corrosion or moisture.
• 5. Replace boundary sensor: If the coil is open‑circuit or damaged, replace the boundary sensor assembly with the correct Yard Force part.

If replacing the sensor does not resolve E11, the main PCB may have a failed input channel and should be replaced by a technician.