BoilerFaultCodesYour boiler is temporarily cooling itself down after finishing a cycle for hot water.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: DHW mode – pump or fan overrun error
What causes this fault?
This occurs when the boiler detects that the internal heat exchanger is still too hot after you have finished using your hot water. To protect the components from heat damage, the boiler continues to run the pump or fan to dissipate the excess heat before it can start a new task. It is usually a normal safety function, but if it stays on the screen for a long time, it could mean a valve is sticking or the pump is starting to slow down.
DIY fix possible
Check that at least one radiator or bypass valve is open to allow heat to dissipateWait for the code to disappear naturally as the boiler settlesEnsure there is enough water pressure shown on the digital display (1.0 to 1.5 bar)
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 S.25 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.