Your boiler is not broken; it is simply letting you know that it has received a request to provide hot water and is currently preparing to deliver it.
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: Hotwaterhandlingmode:Requirement
What causes this fault?
This code appears when a hot water tap is opened or a shower is turned on, triggering the boiler's internal sensors to detect a flow of water. It signifies that the internal diverter valve has successfully shifted into position to prioritise heating your water. It is a normal part of the boiler's operation and simply confirms the system is responding to your request for heat.
DIY fix possible
No action is required as this is a normal status message and not a fault.Ensure your hot water taps are closed if you do not require water.Check your external controls or timer if the message stays on when no water is being used.
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.20 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.