Medium
S.042 on Vaillant ecoTEC plus

Your boiler is temporarily pausing its operation because a safety device connected to the heating system is signaling that it cannot safely exhaust or drain properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

An external unit (e.g. condensate pump or external flue non-return flap) is blocking the burner operation. The unit is in awaiting period.

From this model's manual
Verified against the Vaillant Ecotec Plus installation & service manual.
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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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