I looked at manual above and it mentions only Thermocouple, which is the Two-Wire device pictured above. Diagrams in the above manual show a Two-Wire device, which is a Thermocouple. If Christy found a single-wire sensor, it doesn't seem to be covered in the manual. I looked up how a Flame Sensor works and it's pretty involved. Different ionization rates because the Burner Surface and the Flame Sensor have significantly different surface areas. The flame therefore causes an uneven flow of AC current. Blah Blah Blah. Testing sounds tricky. I think what I'd do is clean the Sensor, its Connection, the top of the Burner, and the joint were the Burner grounds to the rest of the Fridge. I can link the article I found if you like.
