BoilerFaultCodesTechnical description
Low mains voltage
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the incoming electrical voltage from your mains supply has dropped below the minimum level required for the components to function. Most commonly, this is caused by a temporary fluctuation in the local power grid, though it can also indicate a failing printed circuit board (PCB) that can no longer process power correctly.
This fault is slightly more common during internal cold snaps or heatwaves when the national grid experiences high demand, potentially leading to '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.
Find a Gas Safe engineer
Search the official register →