F.65 error, boiler shuts down, PCB very warm to the touch

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

Blocked ventilation around boiler, High ambient temperature, Faulty PCB temperature monitoring, Overloaded PCB due to component failure

Safety: Isolate power before touching internal components.

Steps:

Check that the boiler has adequate clearance and ventilation as per Vaillant installation instructions.
Remove any items stored around or on top of the boiler that may restrict airflow.
Allow the boiler to cool and then reset.

If the error recurs, a technician should inspect the PCB and surrounding components for overheating signs and replace the PCB if necessary.

Hard 4/5

Main Control PCB

Check Price on Amazon

We may earn a commission from links on this page.