BoilerFaultCodesWhat the manual says
Manufacturer manualFuse Type (F1A)
From this model's manual
Verified against the Glow Worm Ultimate System installation & service manual.
What causes this fault?
This fault occurs when the boiler's internal electrical protection system detects an overload or a short circuit, causing a safety fuse to blow. The most common reason is an electrical component, such as the pump or a valve, failing and drawing too much current, which cuts power to the control board to prevent further damage.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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 F1: 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.