F.19 High

Viessmann F.19 Fault Code

Also written as F19 — same fault.

The Viessmann F.19 fault code means: your boiler has lost the connection to the temperature sensor inside your hot water tank, so it currently does not know when your water is hot enough and has stopped heating it.. It appears on 1 Viessmann model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: No DHW heating. Lead break, bottom cylinder temperature sensor.
Typical repair cost £150-250 (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.19 fault code

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

Source

Viessmann F.19 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