BoilerFaultCodesWhat the manual says
Manufacturer manualburner on
From this model's manual
Verified against the Glow Worm/Glow Worm Ultracom 2 Cxi installation & service manual, page 52.
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.
Find a Gas Safe engineer
Search the official register →
Boiler cover options
Avoid the next call-out bill
A cover plan would handle faults like S.04: no call-out fees, no surprise bills.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.
Related fault codes
All 51 fault codes on the Ultracom cxi
Seeing a different code? Every code this model can display, in one place.