High
F.43 on Vaillant ecoTEC plus Aquaplus

Your boiler's internal wiring has developed a communication failure, meaning the safety systems can no longer properly connect to the main control board.

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

Faulty cable loom | Faulty or incorrect loom fitted

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

F.42View →

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