BoilerFaultCodesWhat the manual says
Manufacturer manualSupply voltage under 170v – electric supply error
What causes this fault?
This fault occurs when the electrical current entering your boiler drops to an unsafely low level, preventing the internal computer from functioning. The most common reason is a wider problem with the local power grid or a fault in your home's electrical wiring, though a failing internal circuit board can sometimes misread a healthy supply.
This fault can occasionally occur during extreme winter peaks when the national grid experiences exceptionally high demand, leading to temporary 'brownouts' or voltage drops.
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.
Avoid the next call-out bill
A cover plan would handle faults like F34: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.