BoilerFaultCodesYour boiler has shut down because a sensor has detected that the internal water or exhaust gases have become dangerously hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety temperature limiter in heat exchanger or flue gas temperature limiter has operated
What causes this fault?
This fault occurs when the water inside the boiler or the exhaust gases reach a temperature that is no longer safe, triggering an automatic shutdown to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the system, such as a buildup of limescale or sludge, which causes the heat exchanger to trap too much heat.
This fault is more common when the heating is first turned back on in autumn, as internal pumps can seize up after being inactive throughout the summer.
DIY fix possible
Check that your radiator valves are open and not turned to zeroCheck that your boiler pressure is between 1.0 and 1.5 bar on the pressure gaugePress and hold the reset button for five seconds
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 E9 — no call-out fees, no surprises.
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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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