Medium Warning
56:1 on Viessmann Vitodens 333-F

Your boiler's hot water sensor is reporting an unusually high temperature range, which may prevent your hot water from heating correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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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

DHW temperature adjustable from 10 to 95°C (only for gas fired boilers). Observe the max. permissible DHW temperature

What causes this fault?

This fault occurs when the sensor responsible for monitoring your hot water temperature starts sending irregular or 'out of range' signals to the boiler's internal computer. The most common reason is that the sensor has developed an electrical fault or the internal wiring has become slightly corroded, preventing the boiler from knowing exactly how hot your water is. Because the boiler cannot safely verify the temperature, it may restrict hot water production as a precaution.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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