I had a similar issue with my Dometic. In the area where the flame burns there is the igniter as well as the thermocouple. Initially looking at it I thought they were one in the same because that's the way the water heater works. Turns out the thermocouple had some crud on it that easily broke off with a flat head screwdriver. The fridge would work on propane for a while but because the crud was insulating the thermocouple it eventually shut off the propane because it wasn't detecting enough heat. The thermocouple is in behind the igniter.