BoilerFaultCodesMain 154 Fault Code
The Main 154 fault code means: your boiler has detected that the water is circulating at an unusual speed or temperature difference, often caused by a blockage or a pump issue.. It appears on 1 Main model in our database.
Technical description: Flow / return sensor temperature test
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Main models that show the 154 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Main 154 fault code information on this page is sourced and cross-checked against the official Main service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026