BoilerFaultCodesYour boiler is receiving an incorrect or unusual temperature request for your hot water from the external heating controls.
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 set temperature: Setting value of the hot water temperature demanded by the heating controller.
What causes this fault?
This fault occurs when your external thermostat or heating app sends a temperature command that the boiler doesn't recognize or can't process. The most common reason is a communication glitch or a software mismatch between your wireless controller and the boiler's internal computer.
DIY fix possible
Check your thermostat or heating app to ensure the hot water temperature is set to a normal level (typically 50-60°C).Turn the boiler off and back on at the main isolation switch to reset the communication between the controller and the boiler.Ensure any smart home batteries in your thermostat are not low, as this can cause communication errors.
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 1-b7 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.