BoilerFaultCodesWhat the manual says
Manufacturer manualdomestic hot water demand
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 code appears when the boiler's internal flow sensor detects that water is moving through the hot water pipes. It triggers the burner to ignite so that it can provide an immediate supply of heat to your taps or shower. This is a normal operational message rather than a mechanical failure.
DIY fix possible
Check if any hot water taps have been left running slightlyEnsure your shower is fully turned offNo action is required as this is a normal status message, not a fault
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.10: 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.