BoilerFaultCodesPotterton SF Fault Code
The Potterton SF fault code means: your boiler is currently running in a special service mode used by engineers to test its performance, and it is not actually reporting a fault.. It appears on 1 Potterton model in our database.
Technical description: Calibration Mode (Service Function) - the display will alternate between ‘SF’ and the current boiler temperature and both green LEDs will flash
What causes the Potterton SF fault?
This code appears when the service function has been manually activated, usually by an engineer turning a selector switch to the 'test' position. It physically forces the boiler to run at its minimum or maximum power so that gas levels and performance can be measured accurately. It is not caused by a component failure, but rather by the boiler being placed into a specific operational state for maintenance.
This code is most common during the autumn or spring when homeowners typically book their annual boiler service or safety check.
DIY fix possible
Turn the selector switch to the 'Reset' position and hold for at least 5 seconds.Wait for the display to return to a standard temperature reading.If the code persists, turn the power off and back on at the fused spur switch.
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Gas Safe Register →Potterton models that show the SF fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton SF 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