BoilerFaultCodesYour boiler has detected that hot water isn't moving through the system properly, which is likely caused by 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).
What causes this fault?
This fault occurs when the internal sensors detect that water is getting too hot too quickly because it isn't moving away from the heat exchanger. The most common reasons are a seized circulation pump, a blockage caused by sludge buildup, or an air lock trapped within the pipework.
This issue often appears during the first cold snap of autumn when a pump that has been idle all summer fails to restart.
DIY fix possible
Check if all radiator valves are openEnsure your boiler pressure is between 1.0 and 1.5 barTry resetting the boiler to see if the error clears
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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