F.544 Medium

Viessmann F.544 Fault Code

Also written as F544 — same fault.

The Viessmann F.544 fault code means: your boiler has detected an issue with the valve that regulates the temperature of your heating water, so it has shut that valve to protect your system while keeping the water pump running.. It appears on 4 Viessmann models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Mixer closes. Heating circuit pump is operational.
Typical repair cost £150-300 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Viessmann models that show the F.544 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Viessmann F.544 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026