High
P1 on Worcester Bosch Greenstar 25i (ZWB 7-25)

Your boiler is struggling to begin its initial start-up process, meaning it cannot currently provide heating or hot water until the internal electronic controller is reset or repaired.

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

Start-up sequence step 1 (Appears if start sequence is not completed, potential fuse 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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