BoilerFaultCodesRemeha E12 Fault Code
The Remeha E12 fault code means: your boiler has shut down because it has detected an unsafe build-up of heat or a lack of water circulation within the main system.. It appears on 9 Remeha models in our database.
Technical description: High limit thermostat tripped
What causes the Remeha E12 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
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Gas Safe Register →Remeha models that show the E12 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha E12 fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026