High Lockout
8.C on Worcester Bosch Greenstar CDi Compact

Your boiler has detected an internal communication error between its electronic control components and is unable to start for safety reasons.

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

GFA status (not applicable)

What causes this fault?

This fault occurs when the boiler's internal computer system loses the ability to talk to its electronic components. It is usually caused by a physical break in the internal wiring or a critical failure of the main printed circuit board, which prevents the boiler from performing its safety checks.

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

C1View →C6View →C7View →

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