9 flashes High

Worcester Bosch 9 flashes Fault Code

Also written as 9FLASHES — same fault.

The Worcester Bosch 9 flashes fault code means: your boiler's internal computer has encountered a critical communication error and can no longer control the heating process safely.. It appears on 3 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: Internal error. Check electrical connector contacts, programmer interface module ignition leads are not loose; replace pcb if necessary.
Typical repair cost £280-450 (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 9 flashes fault code

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

Source

Worcester Bosch 9 flashes 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 7 July 2026