High
P1, P2, P3, P4 on Worcester Bosch Greenstar 25 HE Combi

Your boiler has detected an internal computer error that is preventing it from starting up correctly.

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

Internal error.

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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Related fault codes

P1View →P2View →P3View →

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