Error 20
Gardena
Main Control Board Internal Error
Display shows “Error 20 – Internal fault” or “Unexpected error” and the mower will not start.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Firmware corruption, Moisture damage on main PCB, Short circuit from previous component failure, Overvoltage event from power supply
How to Fix / Troubleshooting
Safety first: Switch OFF the mower, remove the key, and disconnect from the charging station.
- Full power reset: Disconnect the battery pack for 5–10 minutes, then reconnect and restart the mower.
- Inspect for moisture: Open the housing and check the main PCB area for signs of water ingress, corrosion, or insect nests. Dry gently if slightly damp; do not use heat guns.
- Check seals: Ensure the top cover gasket and cable grommets are intact to prevent future moisture entry.
- Update firmware (if supported): Use the Gardena app or service tool to update firmware if the model allows.
If the internal fault remains, the main control board will typically need replacement by an authorized service center.
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Repair Difficulty
Professional Required
5/5
Required Part
Gardena Main PCB
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