BoilerFaultCodesRemeha bXX Fault Code
Also written as BXX — same fault.
The Remeha bXX fault code means: your boiler has temporarily stopped working because it has detected a specific operating condition that requires it to pause for safety or system protection.. It appears on 3 Remeha models in our database.
Technical description: Shut-off mode
What causes the Remeha bXX fault?
This fault occurs when the boiler's internal sensors detect that the water temperature is rising too quickly or has exceeded safe operating limits. This is usually caused by a lack of water flow through the heat exchanger, often due to a pump failure or a blockage in the system pipework. To prevent components from warping or melting, the boiler shuts down until the temperature drops back to a safe level.
This issue often surfaces during the first cold spell of autumn when the heating is turned on after a long summer break, as internal pumps can seize during periods of inactivity.
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 bXX fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Remeha bXX 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