F.63 error, boiler locked out, may occur after power surge or PCB replacement

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

Corrupted PCB memory, Incompatible or incorrectly programmed PCB, Electrical surge damage

Safety: Isolate power before accessing electronics.

Steps:

Turn off power for several minutes, then restore and attempt a reset.
If F.63 reappears, the PCB firmware or memory is likely corrupted.
Contact a Vaillant-trained technician to replace and correctly parameterize the PCB according to the boiler model and gas type.

This is not a user-serviceable fault.

Professional Required 5/5

Main Control PCB

Check Price on Amazon

We may earn a commission from links on this page.