How much does it cost to fix Viessmann error code 72:2?

Typical repair cost for the Viessmann 72:2 fault is £90-180 including labour.

72:2 Low

Viessmann 72:2 Fault Code

Q: What does the Viessmann 72:2 fault code mean?

Your boiler has detected that a hot water sensor is reporting a temperature increase when it was not expected to, likely due to a sensor being in the wrong position or failing.

Also written as 722 — same fault.

The Viessmann 72:2 fault code means: your boiler has detected that a hot water sensor is reporting a temperature increase when it was not expected to, likely due to a sensor being in the wrong position or failing.. It appears on 5 Viessmann models in our database.

Technical description: ON during DHW loading to set value 2

What causes the Viessmann 72:2 fault?

This fault occurs when the boiler detects an unexpected rise in temperature within the hot water system, suggesting heat is flowing where it shouldn't. The most common reason is a faulty temperature sensor providing incorrect readings or an internal diverter valve that has become stuck, allowing heat to leak into the water cylinder even when the boiler is only supposed to be heating your radiators.

Typical repair cost £90-180 (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 72:2 fault code

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

Source

Viessmann 72:2 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 27 April 2026