BoilerFaultCodesYour boiler has reached its maximum safe temperature and has shut down to prevent overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Maximum limit of flow temperature
What causes this fault?
This fault occurs when the water inside the boiler gets too hot too quickly, causing the safety sensors to shut the system down. The most common reasons are a pump failure preventing the water from moving or a blockage in the heat exchanger that restricts flow. It can also happen if there is trapped air in the system or if the radiator valves are all closed.
This fault is more common when the heating is first turned on after summer, as pump components can seize during long periods of inactivity.
DIY fix possible
Check that your radiator valves are open and not turned to zero.Ensure your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Press the Reset button for five seconds to restart the boiler.
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 111 — 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.