BoilerFaultCodesYour boiler has sensed that the water leaving the unit is getting too hot and has shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Outlet sensor error for having exceeded the max. outlet temperature
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the water temperature has risen far beyond its safe operating limit. The most common reasons for this are a failing internal pump that isn't moving the hot water away quickly enough, or a faulty sensor that is providing an incorrect heat reading to the control board.
This issue is more common during the first cold snap of autumn when a pump that has been idle all summer suddenly seizes or struggles to circulate water through the heating system.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like A17 — 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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