Boiler shows F.64, temperature sensor or PCB error

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.

Possible Causes

Intermittent NTC sensor connection, Damaged sensor wiring, PCB analogue input fault, Overheating of PCB

Safety: Isolate power and allow boiler to cool.

Check NTC connections: Inspect both flow and return NTC connectors and wiring for looseness or damage.
Check for overheating: Ensure ventilation around the boiler is adequate and that the boiler is not installed in a sealed cupboard without vents.
Engineer diagnosis: If wiring and sensors are OK, the PCB may need replacement.

Hard 4/5

Main Control PCB

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