F.30 Medium

Viessmann F.30 Fault Code

Also written as F30 — same fault.

The Viessmann F.30 fault code means: your boiler has lost the signal from a temperature sensor that monitors the water flow between your heating system and the boiler, which will likely stop your heating from working correctly.. 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: Short circuit, low loss header sensor
Typical repair cost £120-220 (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.30 fault code

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

Source

Viessmann F.30 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