High
A8 on Worcester Bosch CDi Highflow

Your boiler's electronic controls have lost their connection, meaning the main brain cannot communicate with the internal components to start 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

Communication to the BUS system broken

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

A1View →

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