BoilerFaultCodesTechnical 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.