BoilerFaultCodesYour boiler has got too hot and has automatically shut down for safety 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: Safety limiter in flow has tripped.
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power. It is usually caused by a pump failure that stops water from moving or a blockage in the system that prevents heat from being carried away fast enough. In some cases, air trapped in the heat exchanger can also cause a localized hotspot that trips the sensor.
This fault is more frequent in autumn when heating systems are first turned on after a long summer break, as pump components can seize due to inactivity.
DIY fix possible
Check that your radiator valves are open to allow water to circulate.Ensure your system pressure is correct (usually between 1 and 1.5 bar).Press the reset button on the front of the boiler once it has cooled down.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E9 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
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.
Affiliate links — we may earn a commission at no extra cost to you.