BoilerFaultCodesTechnical description
External CH pump
What causes this fault?
This fault occurs when the boiler sends a signal to an external pump to start moving water through your radiators, but it detects that no power is being used or the pump is failing to spin. The most common reasons are a seized pump motor after being left off for a long time, or a loose wiring connection between the boiler's control board and the pump itself.
This issue is frequently seen during the first cold spell of autumn when a pump that has sat idle all summer becomes stuck due to internal debris or limescale.
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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