BoilerFaultCodesYour boiler has detected that water is not moving through the system correctly, which could be due to a blockage or a pump failure.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Primary water circulation fault
What causes this fault?
This fault occurs when the boiler detects that water is not moving quickly enough through the internal pipework to carry heat away, causing the system to protect itself from overheating. The most common reason is a failing internal pump that can no longer circulate the water, or a physical blockage caused by a build-up of debris and sludge within the system.
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.
DIY fix possible
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gaugeEnsure all radiator valves are fully openCheck if any bypass valves are closed
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E125 — no call-out fees, no surprises.
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Potterton Promax is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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