BoilerFaultCodesYour boiler is not broken; it has simply been left in a manual testing mode and needs to be switched back to its normal setting.
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: Not a fault code: Service mode selected to min, press service button to return to normal.
What causes this fault?
This occurs when the service button has been pressed, putting the boiler into a manual override mode typically used by engineers for testing. In this specific state, the boiler is being told to run at its minimum power level indefinitely rather than responding to your thermostat. It is not caused by a mechanical failure, but simply by the control panel being left on the wrong setting.
This issue is more common in autumn, as it often happens after an engineer has performed an annual summer service and forgotten to exit the testing mode.
DIY fix possible
Locate the button with a 'spanner' or 'service' icon on the control panel.Press and hold the button for a few seconds until the flashing light stops.The boiler should return to its normal display and regular operation.
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, Lockout reset: No light — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch Greenstar 25Si 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.