Robot mower displays E13 and does not move even though the boundary signal is present.

Safety first: Turn OFF the mower and remove it from the lawn. Disconnect the battery before disassembling wheels.

• Access wheel encoders: Remove the drive wheel and the protective cover over the motor/gearbox. Locate the encoder disc (slotted or magnet ring) and sensor.
• Clean encoder: Remove grass, mud, or rust from the encoder disc and sensor area using a soft brush and compressed air.
• Inspect sensor: Check that the Hall sensor or optical sensor is firmly mounted and positioned close to the disc without touching it.
• Check wiring: Follow the encoder wires back to the main PCB. Look for breaks, crushed sections, or loose connectors.
• Swap sides (if possible): On some models, you can swap left and right motor connectors to see if the error follows the motor. If it does, the motor/encoder assembly is faulty.

When to replace: Replace the drive motor with integrated encoder if the sensor or disc is damaged or sealed inside the motor housing.