I believe that this is one of the inputs to your Engine Control Computer (the ECU). It could be a bad temperature sensor or a broken wire between sensor and computer.
But it could also indicate a problem with the computer module itself. ECUs are a known trouble component. The frame mounted ECUs get a lot of engine heat and water & end up leaking or swelling up and breaking their internal printed ciruit.
Non-repairable. Replace with new.
I just had the ECU replaced on our 310SG. My error code was coolant temperature instead of air.