BoilerFaultCodesYour boiler has detected that the water inside is reaching temperatures that are either too high or too low for safe operation, causing the system to shut down.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: FAULT POINT F. Primary water temperature too hot (Over 85°C) or too low (Less than 75°C). Likely thermistor sensor, gas pressure, flue blockage, or control board fault.
What causes this fault?
This fault occurs when the internal sensors detect that the water temperature has strayed outside of its safe operating window, usually due to a lack of circulation or incorrect heat levels. The most common reason is a failing temperature sensor (thermistor) providing inaccurate readings, or a blockage within the heat exchanger that prevents heat from transferring correctly. In some cases, a fault with the gas valve or the main control board can cause the burner to stay on too long, leading to overheating.
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 OTHER FAULTS — no call-out fees, no surprises.
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Worcester Bosch 14/19cbi is discontinued — time for a new one?
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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