F64 Fault Code - Vaillant

📌 You must be a Gas Safe registered engineer to remove the boiler cover or replace internal electrical components. Estimated Costs (UK Average) Estimated Part Cost Labor Time NTC Sensor £15 - £30 30 - 60 mins Main PCB £150 - £250 1 - 2 hours Wiring Loom £40 - £80 1 - 2 hours If you'd like to troubleshoot further, tell me:

The pressure switch (also called a flow sensor or diaphragm switch) detects that the pump is moving water. Over time, the rubber diaphragm inside can harden, tear, or stick. If the switch is stuck open, the boiler never gets the "OK" signal. vaillant f64 fault code