BoilerFaultCodesYour boiler is struggling to heat up as quickly as it should, which suggests there is a problem with the water flow or a sensor inside the unit.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow sensor temperature rise incorrect (time taken for flow temperature to rise is too long.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water isn't heating up at the expected speed after the burner ignites. The most common reason is a restriction in water flow caused by a failing pump or a buildup of debris, preventing heat from being moved away from the heat exchanger efficiently.
This issue often surfaces in autumn when the heating is turned back on after a summer of inactivity, which can cause the internal pump to seize or stick.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like 0A16 — 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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