BoilerFaultCodesYour boiler is simply running the pump for a short time after you have used hot water to cool the internal components down safely.
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 is a normal part of your boiler’s operation that happens right after you have finished using a hot tap or the shower. It is triggered because the internal heat exchanger is still very hot, so the pump stays on for a few minutes to move water through the system and dissipate that heat. This protects the internal components from overheating and helps prevent the buildup of limescale.
DIY fix possible
Wait approximately 5 to 10 minutes for the process to finish automaticallyCheck that your hot water taps are fully turned offMonitor the display to see if the code changes to a standby or heating code
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.17 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.