BoilerFaultCodesWhat the manual says
Manufacturer manualCommunication fault between PCB and programming unit (user interface)
From this model's manual
Verified against the Viessmann Vitodens 050 W Bpjd installation & service manual.
What causes this fault?
This fault occurs when the data link between the boiler's main brain and the control screen is broken or interrupted. The most common reason is a loose internal connection or a failure of the delicate wiring that carries signals between the two components.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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