BoilerFaultCodesYour boiler is performing a routine safety check by starting the fan before the burner ignites.
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: fan pre-run
What causes this fault?
This is a normal part of the boiler's startup sequence where the fan clears any leftover gases from the combustion chamber to ensure a safe ignition. It is not a fault, but rather a status update showing that the system is preparing the burner to fire up. If this code stays on the screen without the boiler eventually firing, it may indicate that the fan is struggling to reach the required speed.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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 S.11 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Ultrapower sxi 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.