Medium
Cd on Viessmann Vitodens 300-W

Your boiler has lost its connection with the remote control or internet communication module, which may stop you from controlling your heating via an app or external thermostat.

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

Communication fault Vitocom 100 (KM BUS)

DIY fix possible

Locate the Vitocom 100 communication module near the boilerCheck that the communication cable (KM-BUS) is securely plugged into the moduleTurn the boiler power off at the main fused spur, wait 30 seconds, and turn it back on to reset the connection

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