Vaillant EcoTEC Gas Boiler Diagnostic codes
Vaillant EcoTEC Gas Boiler Error Codes Fault Code Possible Cause D.0 Heating part load error D.1 Water pump overrun – time for heat mode D.2 Max burner anti-cycling period at 20c flow temperature D.3 Hot water flow temperature reading D.4 Current temperature for warm stat sensor D.5 Set value of flow temperature or target value …