BoilerFaultCodesWhat the manual says
Manufacturer manualProduct 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 Ecotec Exclusive installation & service manual.
DIY fix possible
Check your boiler's pressure gauge to see if it has dropped below 1 bar.Use the filling loop or key underneath the boiler to top up the pressure to between 1 and 1.5 bar if it is low.Bleed your radiators starting from the bottom floor upwards to release any trapped air.Reset the boiler once the pressure and air issues have been sorted.
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Related fault codes
All 207 fault codes on the ecoTEC exclusive 835 VUW 356/5-7
Seeing a different code? Every code this model can display, in one place.
conF.00F.00F.01F.01F.02F.02F.03F.03F.10F.10F.11F.11F.12F.12F.13F.13F.20F.20F.22F.22F.23F.23F.24F.24F.25F.25F.26F.26F.27F.27F.28F.28F.29F.29F.32F.32F.33F.33F.35F.35F.42F.42F.49F.49F.55F.55F.56F.56F.57F.57F.61F.61F.62F.62F.63F.63F.64F.64F.65F.65F.67F.67F.68F.68F.70F.70F.71F.71F.72F.72F.73F.73F.74F.74F.75F.75F.77F.77F.78F.78F.80F.80F.81F.81F.82F.82F.83F.83F.84F.84F.85F.85F.90F.90F.94F.94P.00P.01P.02P.04P.06P.14S.00S.01S.2S.02S.3S.03S.04S.05S.06S.07S.08S.09S.09S.10S.10S.11S.11S.13S.13S.14S.14S.15S.15S.16S.16S.17S.17S.19S.19S.20S.20S.21S.21S.22S.22S.23S.23S.24S.24S.25S.25S.26S.26S.27S.27S.28S.28S.29S.29S.30S.30S.31S.31S.32S.32S.33S.33S.34S.34S.36S.36S.37S.37S.39S.39S.40S.40S.41S.41S.42S.42S.46S.46S.54S.54S.55S.55S.56S.56S.57S.57S.58S.58S.59S.59S.76S.76S.86S.86S.88S.88S.92S.92S.93S.93S.96S.96S.97S.97S.98S.98S.99S.99