BoilerFaultCodesYour boiler's main control panel is having trouble talking to the internal computer, meaning you cannot adjust settings or operate the unit effectively.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Control mode - Communication fault – programming unit (internal)
What causes this fault?
This fault occurs when the data link between the boiler's main display screen and its internal control board is interrupted. The most common reason is a loose internal connection cable or a electronic component failure within the programming unit itself. Because these two parts can no longer 'talk' to each other, the boiler cannot receive commands to provide heating or hot water.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like b1 — no call-out fees, no surprises.
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Viessmann Vitodens 333 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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