High
CH PUMP indicator Slow flash on Grant Vortex Pro 15-26

Your boiler's internal control brain is experiencing an electronics failure and can no longer reliably signal the system to move hot water around 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

Slow flash (once every 2 seconds): Indicates a possible fault with the PCB (relay). Replace PCB.

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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