Hughes Caravan Servicing - A link for Truma Combi Panel Fault Codes https://www.truma.com/uk/en/faq/fault-code-on-truma-cp-plus-control-panel W407H is no mains 230V connected so heater wont work on selected Power Options eg Combi , E1 ,E2
Truma CP Plus iNet Ready Control Panel | PRIMA Leisure