Found the following on another RV site:
"Norcold Book Fault Code shows "LI" "oP" meaning High Temp Limit Switch is open, not owner serviceable.
If you've had the most recent Norcold recall installed, go out and remove the external cover from the rear of the frig and see if the red LED is lit on the new high temp controller (black box). if so you need a new one installed. this is a very common problem, especially with the earlier versions of these black boxes used in the latest recall program. "
Hope this helps.