BoilerFaultCodesYour boiler is struggling to move water around the system effectively, which is causing it to shut down to prevent overheating.
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 through the internal pipework quickly enough to carry heat away from the burner. The most common reasons are a failed internal pump, a blockage caused by system sludge, or a valve that has become stuck and is blocking the flow. Because the heat cannot escape, the boiler shuts down immediately to protect its internal components from melting or cracking.
This issue is frequently seen at the start of autumn when heating systems are turned back on after a summer of inactivity, which often causes moving parts like the pump to seize.
DIY fix possible
Check that your radiator valves are fully openEnsure your boiler pressure is between 1.0 and 1.5 bar on the gaugeGently bleed your radiators to remove any trapped air pockets
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.
Affiliate links — we may earn a commission at no extra cost to you.
Potterton Gold HE 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.
Affiliate links — we may earn a commission at no extra cost to you.