BoilerFaultCodesRemeha 12 Fault Code
The Remeha 12 fault code means: your boiler has shut down because a safety circuit has been broken, which is typically caused by the system overheating or an electrical safety switch being triggered.. It appears on 4 Remeha models in our database.
Technical description: Safety interlock
What causes the Remeha 12 fault?
This fault occurs when the boiler's internal safety loop is broken, acting as an emergency stop to prevent damage. It is most commonly triggered because the system has reached an unsafe temperature due to a pump failure or a blockage that stops water from flowing correctly through the heat exchanger.
This issue often surfaces during the first cold snap of autumn when a pump that has been idle all summer fails to restart, causing the unit to overheat immediately.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Remeha models that show the 12 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha 12 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