Medium Warning
59:0 on Viessmann Vitodens 333-F

Your boiler has detected an issue with the sensors that monitor the temperature of your hot water cylinder, which may lead to inconsistent water temperatures.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

DHW cylinder loading: Starting point -2.5K Stopping point +2.5K

What causes this fault?

This fault occurs when the boiler receives inconsistent or missing data from the probe that monitors your hot water tank. The most common reason is a failing temperature sensor or a loose wire connection, which prevents the boiler from knowing exactly how hot your water is. Without this accurate information, the system cannot safely regulate the heating of your cylinder.

Engineer required

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

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