Medium
S.54 on Vaillant ecoTEC plus aquaPLUS

Your boiler has paused briefly because the water inside is heating up too quickly, which usually means the water isn't flowing through the system as fast as it should.

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 flow temperature gradient too steep (approx 10 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 that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 bar on the gaugeCheck for any strange noises that might suggest air is trapped in the pump or radiators

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