P1, P2, P3, P4... High

Worcester Bosch P1, P2, P3, P4... Fault Code

Also written as P1P2P3P4 — same fault.

The Worcester Bosch P1, P2, P3, P4... fault code means: your boiler is struggling to start up its internal computer system and may have a blown fuse or a faulty control circuit.. It appears on 7 Worcester Bosch models in our database.

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: Please wait, initialisation in progress. Replace fuse S12. Otherwise replace control board.
Typical repair cost £120-£450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the P1, P2, P3, P4... fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch P1, P2, P3, P4... fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026