Your boiler has detected an issue with the stability of the electrical power supply coming into your home.

Electricity network frequency error – fluctuation in electricity frequency.

What causes this fault?

This fault occurs when the boiler's internal computer detects that the incoming electrical supply is not staying at a steady frequency. The most common reason is an unstable local power grid or interference from other high-powered appliances in your home that are distorting the electrical signal. If the power supply is consistent, it usually indicates that the boiler's main control board has become oversensitive or damaged and can no longer process the electricity correctly.