Emergency
F.088 on Vaillant ecoTEC Plus 836

Your boiler has lost the electrical signal to the valve that controls the gas supply, meaning it cannot safely start to heat your water or home.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Gas valve assembly not connected. The electrical connection to the gas valve has been interrupted.

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual, page 87.
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 emergency 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.020View →F.027View →F.028View →

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