High
P3 on Worcester Bosch Greenstar 25i (ZWB 7-25)

Your boiler's electronic control system has failed to start up because a small internal protective fuse has blown.

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.

What the manual says

Manufacturer manual

Please wait, initialisation in progress. 24 V fuse blown.

From this model's manual
Verified against the Worcester Bosch Greenstar 25i Zwb 7 25 installation & service manual, page 43.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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