BoilerFaultCodesYour boiler has too much water in the system, causing the pressure to rise to a level that is higher than recommended for safe operation.
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 > 2.8 bar
What causes this fault?
This fault occurs when the water pressure inside your system rises to an unsafe level, usually because the filling loop has been left slightly open or or is leaking water into the system. It can also happen if the internal expansion vessel, which manages water pressure as it heats up, has failed or lost its air charge. In some cases, a faulty plate heat exchanger may be allowing fresh mains water to leak into the central heating circuit.
DIY fix possible
Locate a radiator bleed valve and use a radiator key to slowly release water into a cloth or container.Monitor the pressure gauge on the boiler control panel until it drops back into the green zone (typically 1.0 to 1.5 bar).Ensure the internal or external filling loop valves are tightly closed to prevent more water from entering the system.
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.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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