BoilerFaultCodesYour boiler has switched itself off to prevent damage after detecting that it is getting too hot 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: FAULT POINT D: Overheat lockout. System pressure low, air in system, bypass missing/incorrectly adjusted, pump failure, or overheat thermostat trip.
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety switch to shut the system down. The most common reasons are a lack of water pressure, a failing pump that isn't moving heat away from the boiler quickly enough, or trapped air pockets causing the unit to spike in temperature.
This issue often appears when the heating is first turned on in autumn, as circulation pumps can seize up after being idle throughout the summer.
DIY fix possible
Check the system pressure gauge and top up to 1.5 bar if lowEnsure all radiator valves are fully open to allow water to flowBleed any trapped air from your radiatorsPress the reset button after the boiler has cooled down
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like Lockout light constantly on — 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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