BoilerFaultCodesWhat the manual says
Manufacturer manualSupply voltage too low (< 170V).
From this model's manual
Verified against the Glow Worm Xtramax He installation & service manual, page 33.
What causes this fault?
This fault occurs when the electrical supply entering the boiler drops below a safe threshold, meaning there isn't enough power to run the internal sensitive components. The most common reason is an issue with your home's incoming mains electricity or a failing internal circuit board that can no longer process the voltage correctly.
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.
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