BoilerFaultCodesWhat the manual says
Manufacturer manualWater pressure too high. The system pressure is too high.
What causes this fault?
This fault occurs when the water pressure inside your heating system exceeds the safe limit, often because the filling loop used to top up the system has been left slightly open or is leaking. It can also happen if the expansion vessel, which manages heat-related pressure changes, has failed or if the system has been significantly overfilled during recent maintenance.
This fault is more common in autumn when homeowners top up their system pressure ahead of the heating season and accidentally add too much water.
DIY fix possible
Check that the filling loop valves are tightly closedBleed water from a radiator using a bleed key to reduce system pressureMonitor the pressure gauge until it returns to the normal range (1.0 to 1.5 bar)Reset the boiler if necessary
Avoid the next call-out bill
A cover plan would handle faults like S.41: no call-out fees, no surprise bills.
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Related fault codes
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Seeing a different code? Every code this model can display, in one place.