Medium Warning
76:0 on Viessmann Vitodens 300-W

Your boiler's internal communication system has stopped talking to a network expansion module, which may affect how advanced heating zones or external controls are managed.

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

Without LON communication module

What causes this fault?

This fault occurs when the boiler's main control center loses touch with the specialized communication module that talks to your smart thermostats or external heating components. The most common reason is a loose internal connection cable or a hardware failure within the communication module itself, preventing the system from synchronizing your heating demands.

Engineer required

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

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