BoilerFaultCodesYour boiler is having trouble communicating with the internal pump that moves hot water through your radiators, which may prevent your heating from working correctly.
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: Control mode, max. pump speed - Communication fault-variable speed heating circuit pump, heating circuit A1
What causes this fault?
This fault occurs when the boiler's main control board loses its electronic connection with the internal circulation pump. It is usually caused by a loose or damaged wiring connection between these two parts, or a total failure of the pump's internal electronics. Without this communication, the boiler cannot adjust the flow of water around your home and will stop heating for safety.
This fault often appears at the start of autumn when the heating is turned on for the first time after summer, as pump components can seize or struggle after long periods of inactivity.
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 C7 — no call-out fees, no surprises.
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