High
A5 on Worcester Bosch Greenstar 25i (ZWB 7-25)

Your boiler is having trouble reading the temperature of the internal hot water store, so it has stopped producing hot water to prevent an error.

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

Heat store NTC sensor 2 defective

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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