BoilerFaultCodesYour boiler has detected that the water returning to the unit is much too hot, suggesting it isn't circulating properly through your radiators or pipes.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Return sensor above 95 °C
What causes this fault?
This fault occurs when water cannot move away from the boiler quickly enough, causing the temperature at the return pipe to spike dangerously high. The most common reasons are a seized internal pump failing to push the water or a major blockage in the pipework or heat exchanger that is strangling the flow. It can also be caused by a faulty sensor sending an incorrect high-temperature reading to the control board.
This fault often appears during the first cold spell of autumn when heating systems are turned back on after months of inactivity, which can cause internal pump components to seize.
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barCheck if any bypass valves are closed or if there is a blockage in the system
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A boiler cover plan would cover faults like b19 — no call-out fees, no surprises.
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