BoilerFaultCodesYour boiler has detected that the internal water temperature is higher than it should be, causing the system to shut down to prevent damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Actual temperature: Flow temperature at the flow temperature sensor.
What causes this fault?
This fault occurs when the water leaving the boiler exceeds its safe temperature limit, causing the system to shut down for safety. The most common reasons are a blockage in the pipework, a pump that has failed to circulate the water, or a buildup of debris inside the heat exchanger that restricts water flow.
This fault is more common when heating is first turned on after a long summer break, as internal pump components can seize during periods of inactivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 1-A5 — 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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