Fast flash (Reset button Off) High

Worcester Bosch Fast flash (Reset button Off) Fault Code

Also written as FASTFLASHRESETBUTTONOFF — same fault.

The Worcester Bosch Fast flash (Reset button Off) fault code means: your boiler has detected a critical internal error and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.. It appears on 1 Worcester Bosch model 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: Volatile lockout. Check: Temperature sensor (8000-20,000Ω); Low voltage wiring harness / connections to sensor; Fan / fan harness / connections to fan; Code plug fitted.
Typical repair cost £150-300 (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 Fast flash (Reset button Off) fault code

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

Source

Worcester Bosch Fast flash (Reset button Off) 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