High
DHW PUMP Slow flash on Grant Vortex Eco External Floor Standing

Your boiler's control computer is failing to communicate correctly with the water heating pump, which means the system cannot reliably produce hot water.

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

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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