Emergency
S.63 on Vaillant ecoTEC plus 937 VUI GB 376/5-5

Your boiler has detected an issue with the quality of the gas burning inside, meaning it has safely shut down to protect your home.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Gas family check unsuccessful: Combustion quality outside permissible range (see also F.93).

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 937 07 2012 Isim 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 is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.93View →F.28View →F.29View →

All 72 fault codes on the ecoTEC plus 937 VUI GB 376/5-5

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.35F.42F.49F.52F.53F.54F.56F.57F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.78F.80F.81F.83F.84F.85F.90F.91F.92F.93S.04S.30S.31S.32S.34S.39S.40S.41S.42S.46S.53S.54S.57S.58S.61S.62S.76S.96S.97S.98

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