Low
S.04 on Glow-worm Ultracom 2 CXI

Your boiler is working normally and is currently firing up to provide hot water for your taps or showers.

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

burner on

From this model's manual
Verified against the Glow Worm Ultracom 2 Cxi installation & service manual, page 52.
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 is a status code rather than a fault, appearing when you turn on a hot tap or start a shower. It indicates that the boiler has successfully detected a demand for water and has lit the burner to begin the heating process. You will see this code briefly every time the boiler is actively working to provide hot water to your home.

DIY fix possible

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

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