High
F75 on Vaillant ecoTEC Plus 826

Your boiler is struggling to detect water moving through the system properly, which is preventing it from safely starting up.

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

Flow rate achieved is insufficient during the purge programme (in conjunction with diagnostic code D.149=8).

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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