I copied this from another forum.
"This error means that the control board is not getting communication from the eyebrow board, which is the display board at the top. On the back of the fridge you will find the main fridge control board, which is protected by a black plastic cover. Remove this cover and you should see the board. Approximately in the center of the circuit board, you will see a terminal marked D+, which should have a wire coming out of it. This is the power wire to the eyebrow board. If this wire is even a little loose, or the wire is loose in the connector, you could easily get this error. Please check that connector to make sure it is tight on the board and the wire is tight in the connector. To the left of this connector, on the left edge of the board at the top, is the communications harness going to the eyebrow board. Also check this connector to make sure it is secure on the board.
If this still doesn't solve your problem, go back inside the coach and carefully remove the top panel where the display and control panel is. Inspect the connectors coming into the eyebrow board. If they are secure and undamaged, you will probably have to replace the eyebrow board. However, before doing this, it is probably a good idea to have the main board tested, as that could also be the problem. If you remove the main control board at the back of the fridge, you can take that to your local RV service center where they will be able to test it for you. If the main board fails, you need to replace it. If it passes, and you have thoroughly checked the connections, you should replace the eyebrow board.
Also, just as a sanity check, test the voltage coming into the fridge to make sure it is close to 12V. Also check the fuses on the board to make sure they are okay."*
"Sabre owners united"