High
S.39 on Vaillant ecoTEC exclusive

Your boiler has temporarily shut down because an external safety device, such as a condensate pump or an overheat sensor, has told it to stop running to prevent damage.

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

Contact thermostat triggered: 'Burner off contact' has responded (e.g. surface-mounted thermostat or condensate pump)

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.22View →F.25View →

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