Medium
S.39 on Vaillant ecoTEC plus 618 H system A VU GB 186/5-5 A

Your boiler has temporarily stopped heating because a safety switch—such as the one for the condensate drain—has triggered to prevent a blockage or overflow.

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

"Burner off contact" has responded (e.g. contact thermostat or condensate pump)

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 832 Lpg Vuw Gb 326 5 5 4704459 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.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.28View →F.29View →S.30View →

All 94 fault codes on the ecoTEC plus 618 H system A VU GB 186/5-5 A

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.42F.49F.52F.53F.54F.56F.57F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.77F.78F.80F.81F.83F.84F.85F.90F.91F.92F.93S.00S.01S.02S.03S.04S.05S.06S.07S.08S.10S.11S.13S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.40S.41S.42S.46S.53S.54S.57S.58S.61S.62S.63S.76S.96S.97S.98

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