High Lockout
8.d on Worcester Bosch Greenstar CDi Compact

Your boiler has detected an internal electronics communication error, which has caused it to stop working for safety.

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 error (not applicable)

What causes this fault?

This fault occurs when the boiler's main control board loses its digital connection with the internal safety sensors or ignition components. The most common reason is a physical failure within the printed circuit board's circuitry or a loose connection in the internal wiring loom that prevents data from flowing correctly.

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 →

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