High Lockout
E317 on Potterton Assure Combi / System

Your boiler has detected an issue with the electrical frequency coming from the mains power supply or a fault within its internal control board.

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

Wrong power supply (HZ)

What causes this fault?

This fault occurs when the boiler's internal computer detects that the electrical supply timing, known as frequency, does not match the required UK standard. This is usually caused by a glitch in the local power grid or a malfunctioning control board inside the boiler that can no longer process the incoming electricity correctly. In rare cases, using a backup generator or an unstable power source can also trigger this shutdown.

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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Related fault codes

E118View →

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