BoilerBuddy · Viessmann guide

Viessmann boiler fault codes and symptoms

BoilerBuddy helps you diagnose boiler problems, work through minor checks, and escalate major problems to a Gas Safe engineer. Start with the exact code and range shown on your appliance; meanings can differ between models.

From the fault-code directory

Common Viessmann codes and symptoms

These examples link to existing records for their specific boiler ranges. Open the matching record for its full context and guidance.

  • Vitodens 050-W

    Code 767: 767

    Flue-gas temperature is too high.

  • Vitodens 050-W

    Code 799: 799

    Heating-circuit pump electrical fault; the manual states that the system cannot operate without flow.

  • Vitodens 100-W heat-only

    Code 50: 50

    Flue-gas temperature sensor short circuit.

  • Vitodens 100-W heat-only

    Code 59: 59

    Undervoltage or power-supply fault; the burner is locked out, so there is no heating or domestic hot water.