BoilerFaultCodesYour boiler has been manually set to run at its lowest power setting for servicing and just needs to be switched back to its normal operating mode.
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: No light Service mode selected to min, press service button to return to normal.
What causes this fault?
This occurs because the 'Service' button has been pressed, manually locking the boiler into its lowest firing rate for testing purposes. It is not caused by a component failure, but rather by the control system being left in a diagnostic mode intended for engineer use. To fix it, the boiler simply needs to be toggled back to normal operation by pressing the service button again.
DIY fix possible
Locate the service button (represented by a spanner icon or 'Service' label) on the control panel.Press and hold the service button for roughly 5 seconds until the light stops pulsing.The boiler should return to normal operation and your heating should resume.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 2 pulses — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch Greenstar 12i System is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.