Medium
S.53 on Vaillant ecoTEC exclusive 627 VU 256/5-7

Your boiler has temporarily paused because the water is not flowing through the system fast enough, causing it to heat up too quickly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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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

Waiting time: Water shortage / Product is within the waiting period of the modulation block/operating block function as a result of water deficiency (flow/return spread too large)

From this model's manual
Verified against the Vaillant/Vaillant Vaillantpro 0020193966 04 Ecotec Exclusive System Installation I 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.

DIY fix possible

Check that all radiator valves (TRVs) are fully openEnsure the boiler pressure is between 1.0 and 1.5 bar on the displayCheck for any blocked magnetic filters or air locks in the radiators

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Related fault codes

F.20View →F.22View →F.24View →S.54View →

All 72 fault codes on the ecoTEC exclusive 627 VU 256/5-7

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

F.00F.01F.02F.03F.10F.11F.12F.13F.20F.22F.23F.24F.25F.26F.27F.28F.29F.32F.33F.35F.42F.49F.55F.56F.57F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.77F.78F.80F.81F.82F.83F.84F.85F.90F.94S.34S.36S.37S.39S.40S.41S.42S.46S.54S.55S.56S.57S.58S.59S.76S.86S.88S.92S.93S.96S.97S.98S.99

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