High
Fast flash (Reset button Off) on Worcester Bosch Greenstar i Junior

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.

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

Volatile lockout. Check: Temperature sensor (8000-20,000Ω); Low voltage wiring harness / connections to sensor; Fan / fan harness / connections to fan; Code plug fitted.

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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