Truma
Hi Davy, I have'nt a clue about Truma. My complete system runs with Truma. I also have the same problem with a yellow flame on both the frige and and heating. I let it run for a while and it corrects it's self. I get a spluttering and burping noise, I think, like you say, it is the CO2. Let it run and see what happens. Mine always clears in the end. If not, it could be the tiny jet holes are dusty or slighty blocked due to long standing without use.