BoilerFaultCodesYour boiler is notifying you that it has adjusted the temperature settings for its pre-heat function to ensure hot water is ready when needed.
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: Off set for warm start target value
What causes this fault?
This occurs when the boiler’s internal software automatically shifts the target temperature for the 'warm start' feature to ensure the heat exchanger stays ready for use. It is usually triggered by the control system detecting that the internal water temperature has dropped below a specific threshold required for instant delivery. This is a self-correcting logic adjustment rather than a mechanical failure.
This notification is more frequent during colder months when lower ambient temperatures cause the water inside the boiler to cool down more rapidly between uses.
DIY fix possible
No action is typically required as this is often an advisory status code rather than a hard fault.If hot water temperatures feel inconsistent, check your boiler's hot water temperature dial/setting.Perform a simple reset by pressing the 'flame' or 'reset' button to see if the status clears.
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 D.73 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.