BoilerFaultCodesYour boiler is briefly running the internal pump after you have finished using hot water to safely move heat away from the system.
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 overrun. The pump overrun for domestic hot water mode is activated.
What causes this fault?
This occurs when you finish using a hot tap and the boiler needs to dissipate the high levels of residual heat left inside the heat exchanger. The internal pump continues to run for a short period to move this hot water away, preventing the internal components from overheating or becoming damaged by trapped heat. It is a normal safety function rather than a failure of any specific part.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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A boiler cover plan would cover faults like S.27 — no call-out fees, no surprises.
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