Low
S.01 on Glow-worm Ultracom sxi

Your boiler is currently preparing itself for ignition and checking that the safety fan is working correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

fan pre-run

From this model's manual
Verified against the Glow Worm Ultracom 2 Sxi installation & service manual, page 55.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This status code occurs when the boiler's internal computer begins the start-up sequence and tells the fan to spin up. It is checking that the fan can reach the correct speed to safely clear out any leftover gases before the burner ignites. The most common reason for this appearing is simply that the boiler is responding to a demand for heating or hot water.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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