High
A8 on Worcester Bosch 35 RSF

Your boiler has lost its connection to the external heating controls, meaning the thermostat and the boiler are no longer talking to each other.

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

Break communication to FX sensor controls electrical connections need checking.

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 →EAView →

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