44 Medium

Viessmann 44 Fault Code

The Viessmann 44 fault code means: your boiler has detected an electrical fault with a sensor that controls the temperature for a specific part of your heating system, which may prevent that area from warming up properly.. It appears on 2 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, flow temperature sensor, heating circuit 3 (with mixer)
Typical repair cost £120-£200 (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 44 fault code

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

Source

Viessmann 44 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