BoilerFaultCodesYour boiler's internal computer is having trouble communicating with an external control or smart thermostat connected to it.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: BUS communication fault: Incorrect BUS subscriber connected.
What causes this fault?
This fault occurs when the boiler's main computer chip loses its ability to 'speak' to your wall thermostat or smart controller. It is usually caused by a loose connection in the wiring, a faulty circuit board, or an incompatible smart hub being plugged into the system. Essentially, the boiler has received a signal it doesn't understand and shuts down as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like Fault 01 / 201 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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