High
DHW pump on Grant Vortex Blue

Your boiler is struggling to heat your hot water correctly because of a communication issue between its sensors and the internal computer.

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

If flashing this indicates either a store thermistor or PCB fault

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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