BoilerFaultCodesYour boiler is working perfectly and is currently running specifically to provide heat for your radiators.
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: Display shows S.04 if the product is working correctly in heating mode.
What causes this fault?
This is a normal status code rather than a fault, appearing whenever you turn your thermostat up and the boiler begins burning gas to heat your home. It indicates that the internal pump is circulating water through your radiators and the burner is firing to reach your desired temperature. No action is required as this simply confirms the system is performing its primary function.
You will see this code much more frequently during the autumn and winter months when the central heating is used regularly to keep the property warm.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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.04 — no call-out fees, no surprises.
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