Combi E in mixed mode (combined gas and electric heating operation):
Warning indicates lack of gas supply. The heater now only runs in electric mode.
Restore the gas supply for example by connecting a new gas cylinder.
On your control panel you then switch to pure gas mode of your heating system – the warning message changes to error message 507 or 516.
Remove the error as described here: www.truma.com/int/en/faq/remedy-fault-507-516-517
