F.64
Vaillant
Electronics Overtemperature / Sensor Fault
F.64 electronics temperature fault; appliance may shut down intermittently
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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
Overheating of control board area, Blocked ventilation around appliance, Faulty PCB temperature sensor, Loose heat sink or poor thermal contact on PCB
How to Fix / Troubleshooting
Safety: Isolate power before accessing the control compartment.
- Check installation clearances: Ensure the heater has the minimum clearances specified by Vaillant for ventilation and cooling.
- Inspect for heat sources: Verify that external heat sources (e.g. ovens, radiators) are not affecting the appliance.
- Clean ventilation paths: Remove dust and debris from around the PCB and any cooling slots.
- Inspect PCB: Look for signs of overheating, discoloured components, or damaged temperature sensor on the board. Replace the PCB if damage is evident or if F.64 persists.
- Reassemble and test: Restore power and monitor operation under normal load.
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Repair Difficulty
Hard
4/5
Required Part
Main Control PCB
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