High Lockout
E40 on Warmhaus Enerwa / Priwa

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

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.

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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