High
59 on Alpha Intec 50CS

Your boiler is struggling to read the electricity coming from your home's power supply, preventing it from starting up safely.

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

Mains supply voltage frequency block - The PCB detects an incorrect mains supply voltage frequency

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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