High
F.22 on Vaillant Turbomax 824/828

Your boiler has detected that there is either too little water inside the system or that the internal pump is failing to move the water around as it should.

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.

What the manual says

Manufacturer manual

Dry fire protection No water in appliance, pump cable defective, pump blocked or defective, pump output too low

From this model's manual
Verified against the Vaillant Turbomax 824 828 installation & service manual, page 40.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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.23View →F.24View →

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