F12
Saunier Duval
User Interface / Display Board Communication Fault
Furnace shows F12, unit may not respond to user interface commands
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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
Loose ribbon cable between display and main PCB,Faulty display board,Moisture ingress into control panel,Main PCB communication failure
How to Fix / Troubleshooting
Safety first: Disconnect power before removing the front panel or control fascia.
- Inspect connections: Remove the control panel cover and locate the ribbon cable or harness connecting the display board to the main PCB. Ensure it is fully inserted and not damaged.
- Check for moisture: Look for signs of condensation or water ingress around the control panel. Dry the area thoroughly and identify the source of moisture (e.g., flue leaks, room humidity).
- Visual inspection of boards: Examine both the display board and main PCB for burnt components, corrosion, or cracked solder joints. Do not attempt component-level repair unless qualified.
- Test with replacement panel: If available, test with a known-good Saunier Duval display board. If the fault clears, replace the original display board.
- PCB replacement: If the display is good but communication still fails, the main PCB may need replacement by an authorized service technician.
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Repair Difficulty
Hard
4/5
Required Part
Display / User Interface Board
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