BoilerFaultCodesYour boiler has switched itself off because it has reached an unsafe temperature, usually due to a lack of water flow or a circulation problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety thermostat operated
What causes this fault?
This fault occurs when the water inside the boiler gets too hot, triggering a safety switch to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the system pipes that traps heat inside the heat exchanger.
This issue is more frequent when the heating is first turned on in autumn, as circulation pumps can seize up after being inactive throughout the summer.
DIY fix possible
Check if your radiator valves are openCheck the boiler pressure gauge and top up to 1.5 bar if lowPress the 'R' or 'Reset' button for 2 seconds once the boiler 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 E110 — 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.