Medium
S.53 on Vaillant ecoTEC plus aquaPLUS

Your boiler has temporarily paused because it cannot sense enough water flow to operate safely.

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

Delay mode due to lack of water in system (~2,5 mins.)

From this model's manual
Verified against the Vaillant Ecotec Plus Aquaplus installation & service manual, page 38.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check the pressure gauge on the front of the boilerIf the pressure is below 1.5 bar, use the filling loop handles underneath the boiler to top it upEnsure all radiator valves are open to allow water to circulate freely

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