High Lockout
Fast flash / Off on Worcester Bosch 28i RSF

Your boiler has shut itself down for safety because it has detected a significant electrical or mechanical issue with its internal components.

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.

What causes this fault?

This fault occurs when the boiler's internal computer, the Printed Circuit Board, suffers a critical failure or receives abnormal electrical signals it cannot process. The most common reasons are a malfunctioning circuit board, a faulty ignition system that is confusing the controls, or a sudden electrical surge that has damaged the sensitive internal components.

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.

Find a Gas Safe engineer
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