Low
S.04 on Glow-worm Ultracom sxi

Your boiler is operating normally and is currently heating up to provide warmth or hot water.

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 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 is actually a normal status message rather than a fault, appearing when the boiler has successfully ignited the burner to meet a demand for heating or hot water. It indicates that the internal components have completed their safety checks and the boiler is now actively burning gas to heat your home. You do not need to take any action, as this code simply confirms the system is working as intended.

You will see this code more frequently during the winter months when your heating is running regularly to keep your home warm.

DIY fix possible

No action is required as this is an status update rather than a fault.Check your thermostat settings if you did not expect the heating to be on.Monitor the display to see if it changes once the home reaches the desired temperature.

Find a Gas Safe engineer
Search the official register →

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

Related guides you might find useful