BoilerFaultCodesPotterton Green light flashing slowly Fault Code
Also written as GREENLIGHTFLASHINGSLOWLY — same fault.
The Potterton Green light flashing slowly fault code means: your boiler is currently in standby mode and is working correctly, simply waiting for your thermostat or programmer to tell it that you need heat.. It appears on 3 Potterton models in our database.
Technical description: Standby or lack of call for heat (Switch live demand)
DIY fix possible
Check your room thermostat is turned up to a temperature higher than the current room temperature.Ensure your heating timer or programmer is set to 'ON' for the current time period.Verify that the hot water cylinder thermostat is also calling for heat if you have a system with a hot water tank.
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Potterton models that show the Green light flashing slowly fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Green light flashing slowly 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 7 July 2026