BoilerFaultCodesYour boiler has shut down because it has detected an unsafe build-up of heat or a lack of water circulation within the main system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High limit thermostat tripped
What causes this fault?
This fault occurs when the water temperature inside the boiler exceeds a safe limit, causing the safety sensors to trigger a complete shutdown. The most common reasons are a failed pump that isn't moving water away from the heat exchanger quickly enough, or a blockage caused by a build-up of sludge and debris within the system. It can also be triggered if there is trapped air in the pipes or if the water pressure has dropped too low.
This issue is most frequently seen at the start of autumn when heating systems are turned back on after a long summer break, as pumps can often seize or stick during periods of inactivity.
DIY fix possible
Check that your boiler pressure gauge is between 1.0 and 1.5 barEnsure all radiator valves and internal bypass valves are open to allow water flowPress the 'Reset' button on the control panel 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 E12 — no call-out fees, no surprises.
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Remeha Quinta 115 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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