BoilerFaultCodesYour boiler has detected that water is not circulating correctly through the system, causing the safety mechanism to stop the heater.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Go to section 'C'. If regular resetting is required or appliance still does not operate investigation is necessary.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water isn't moving through the unit quickly enough to safely carry heat away. The most common reasons are a failed circulation pump that can no longer push the water, or a perished rubber diaphragm inside the flow switch that is failing to trigger the ignition sequence.
This issue is frequently seen in autumn when heating systems are switched back on after a long summer break, as pumps can often seize or stick during periods of inactivity.
DIY fix possible
Check that the system pressure gauge is between 1.0 and 1.5 barOpen all radiator valves fully to ensure water can flowEnsure the external filling loop valves are tightly closed
Find a Gas Safe engineer
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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