BoilerFaultCodesYour boiler is currently in a manual testing mode used by engineers to check emissions, which means it is running at a fixed output rather than following your thermostat.
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: Chimney sweep demand
What causes this fault?
This code appears when the 'chimney sweep' mode has been manually activated via the boiler's control panel. It is not an internal component failure, but rather a specific setting that forces the burner to run at a fixed speed for testing purposes. If you didn't turn this on yourself, it is likely an engineer left the mode active after completing a service or gas safety check.
DIY fix possible
Locate the 'Exit' or 'Back' button on the boiler control panel.Press and hold the button for a few seconds to cancel the test mode.The display should return to the standard temperature or status screen.
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