BoilerFaultCodesYour boiler has stopped working because water is not moving through the system correctly, which could be due to a blockage or a pump issue.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Circulation Fault (Primary Circuit)
What causes this fault?
This fault occurs when the boiler detects that water is not moving around the internal system fast enough to carry heat away from the burner. The most common reasons are a seized internal pump that has failed to start or a build-up of sludge and debris blocking the narrow pipes within the main heat exchanger. When the water stays still, it overheats almost instantly, triggering a safety shutdown to prevent damage.
This issue often surfaces at the start of autumn when the heating is turned on for the first time after summer, as the pump can seize up during 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 E125 — no call-out fees, no surprises.
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