High Lockout
F0 on Worcester Bosch Greenstar Ri

Your boiler's internal computer has encountered a glitch or a hardware failure, preventing it from running properly.

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.

What causes this fault?

This fault occurs when the boiler's main control board loses its ability to process data correctly or experiences a communication breakdown between internal components. It is often caused by a sudden electrical surge, moisture entering the control box, or simply the natural degradation of the solder points and microprocessors over time.

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

FdView →F7View →

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