BoilerFaultCodesYour boiler has too much water in the system, which is causing high pressure and has triggered a safety shutdown to protect the components.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: Water pressure >2.9bar
What causes this fault?
This fault occurs when the internal water pressure exceeds safe operating limits, often because the filling loop used to top up the system has been left slightly open or is leaking. It can also be caused by a failure in the expansion vessel, which is the part responsible for managing the natural pressure increase that happens when water heats up.
This issue often appears at the start of autumn when homeowners turn their heating back on after a long break, causing the water to expand and reveal underlying pressure problems.
DIY fix possible
Check that the filling loop valves (the blue handles or silver lever) are fully closed.Locate a radiator and use a bleed key to release water into a container until the pressure gauge on the boiler drops to 1.5 bar.Restart the boiler once the pressure is back in the green zone.
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A boiler cover plan would cover faults like S.41 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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