BoilerFaultCodesPotterton A41 Fault Code
The Potterton A41 fault code means: your boiler has stopped working because water is not circulating through the system properly, often due to a pump issue or a closed valve.. It appears on 1 Potterton model in our database.
Technical description: System flow fault. Check pump operation and speed setting. Check by-pass isolating valve is open
What causes the Potterton A41 fault?
This fault happens when the boiler detects that water isn't moving through the internal pipework quickly enough to safely carry heat away from the burner. The most common reason is a failing circulation pump that can no longer push the water, or a blockage such as a closed valve that is choking the flow. To prevent the unit from overheating, the system shuts down as a safety precaution.
This issue often surfaces in autumn when the heating is turned back on after a long summer break, as internal pump components can seize up 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 →Potterton models that show the A41 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton A41 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026