Mains On (Green) light flash Low

Potterton Mains On (Green) light flash Fault Code

Also written as MAINSONGREENLIGHTFLASH — same fault.

The Potterton Mains On (Green) light flash fault code means: your boiler is correctly receiving electrical power and is currently in standby mode, which is the normal operational state.. It appears on 1 Potterton model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Mains electricity supply is On

DIY fix possible

Check your thermostat or programmer settings to ensure there is a demand for heating or hot waterEnsure the boiler's mode selector switch is set to the desired setting for heating and hot waterAdjust your room thermostat to a higher temperature to trigger the firing process

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Potterton models that show the Mains On (Green) light flash fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Potterton Mains On (Green) light flash 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