Robot mower displays E4 and will not start; often occurs when trying to leave the charging station.

Safety first: Turn OFF the mower and unplug the charging station from mains before touching any wiring.

Steps to diagnose:

• 1. Check charging station LEDs: Most Yard Force bases have an LED indicating loop status. Refer to your manual: a flashing or off LED usually means a boundary fault.
• 2. Inspect boundary connections: At the base, remove the boundary wire from the terminals. Trim 1 cm of insulation to expose fresh copper and reconnect firmly. Ensure the wires are in the correct terminals (left/right).
• 3. Walk the perimeter: Follow the boundary wire around the garden. Look for cuts from edging tools, animal damage, or pulled‑out stakes. Pay attention to flower beds and path crossings.
• 4. Test for breaks: Use a simple wire break locator or a multimeter set to continuity. Disconnect both ends at the base and test across the loop. Infinite resistance indicates a break.
• 5. Repair damaged sections: Cut out damaged wire and rejoin using waterproof boundary wire connectors approved for Yard Force. Bury or peg the repair securely.
• 6. Check base electronics: If the wire is intact and connections are good but the base LED still indicates a fault, the boundary transmitter board in the charging station may be defective and require replacement.

After repair: Reconnect power to the base, confirm the loop LED is solid (healthy), then power ON the mower and clear the E4 error.