Medium
S.54 on Vaillant ecoTEC plus 412 VU 126/6-5 OVZ

Your boiler is temporarily pausing because it has detected that the water pressure or the flow of water inside your heating system is not moving correctly.

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

Waitingperiod:Lowwaterpressureinthecircuit(flow/returnspreadtoolarge)

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 610 installation & service manual, page 33.
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 your boiler pressure gauge; if it is below 1 bar, top it up using the filling loopEnsure all radiator valves are fully open to allow water to circulate freelyCheck for any obvious leaks near the boiler or radiators

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Related fault codes

F.22View →F.24View →

All 72 fault codes on the ecoTEC plus 412 VU 126/6-5 OVZ

Seeing a different code? Every code this model can display, in one place.

Connectiond.02d.10d.11F.00F.01F.10F.11F.13F.20F.23F.24F.25F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.77F.78F.83F.84F.85F.86F.87F.88F.91P.01S.0S.01S.02S.03S.04S.05S.06S.07S.08S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.39S.42S.46S.53S.88S.91S.96S.98S.99S.108S.109

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