BoilerFaultCodesYour boiler has detected that hot water is being drawn through the system, often serving as an advisory notification rather than a breakdown.
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 flow rate: Hot water flow rate.
What causes this fault?
This code is triggered when the boiler's internal sensor detects water moving through the hot water pipes, even if you haven't turned on a tap. It often occurs due to a 'passing' tap that isn't fully shut off, a minor leak in the pipework, or a sensor that has become overly sensitive or faulty. Effectively, the boiler is simply notifying you that it is working to heat water because it believe there is a demand.
DIY fix possible
Check that all hot water taps in the property are fully closedInspect for any dripping taps or leaking shower headsMonitor the display to see if the code clears once water usage stops
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like 1-b2 — no call-out fees, no surprises.
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