High
d.16 on Vaillant Ecomax Condensing 600/800 series

Your boiler is having trouble communicating with the pump responsible for moving water through your heating system, which means it cannot circulate heat effectively.

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

2ndpump

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.75View →

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