Fixed the cooling temp indication/engine hot message problem this morning. It was the sensor. Put a new one in and drove it for a mile with the gauge still not moving + engine hot message on the display and cooling fans running full speed. As the engine warmed up, the new sensor must have crossed a point where the computer decided it could trust it again, and everything returned to normal. The gauge shot up to about 1/3 on the scale, and continued indicating normally from there. The message went away and the fans shut off. Boom! I love easy fixes.