BoilerFaultCodesYour boiler has too much water in the system, causing it to shut down to prevent damage from excessive pressure.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: High water pressure due to excessive water pressure or safety valve error
What causes this fault?
This fault occurs when the water pressure inside your heating system exceeds the safe operating limit. The most common reason is that the filling loop was left slightly open after topping up the system, or the internal expansion vessel has lost its air charge and can no longer balance the pressure changes as the water heats up. In some cases, a leaking internal component might be allowing fresh mains water to constantly enter the system.
This fault often appears when you first turn the heating back on for autumn, as the expansion of heating cold water can push an already high-pressure system over the safety limit.
DIY fix possible
Check that the filling loop valves under the boiler are tightly closed.Locate a radiator bleed valve and use a key to release water into a container until the pressure gauge on the boiler drops to 1.5 bar.Restart the boiler to see if the fault clears.
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A boiler cover plan would cover faults like E03 — 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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