50 High

Viessmann 50 Fault Code

The Viessmann 50 fault code means: your boiler has stopped providing hot water because the internal sensor that measures water temperature has detected a technical fault or a short circuit.. It appears on 12 Viessmann models 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: Burner blocked. Short circuit - DHW temperature sensor (combi boiler).

What causes the Viessmann 50 fault?

This fault occur when the boiler's control board receives an impossible electrical signal from the Domestic Hot Water sensor, suggesting the component has failed internally. It is usually caused by a 'short circuit' where the sensor's internal wiring has degraded or succumbed to moisture, preventing the boiler from safely monitoring how hot your water is. In some cases, the issue may also lie with a loose or damaged cable harness connecting the sensor to the main computer.

Typical repair cost £120-190 (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 50 fault code

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

Source

Viessmann 50 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