My scanner is currently reading crazy high coolant temps, like 2000 degrees F when the engine is cold and off. It gets crazier when the engine is on. The dash gauge appears normal.

Is there more than one sensor? I know of the one on the top of the engine by the fuel rail. Could the sensor I'm seeing with the scanner be different than the one supplying the dash gauge? If not, then I'm guessing it's a scanner issue of some kind.

 

Did you get to the bottom of this?

 

Best I can tell it was a scanner issue. i can only find one temp sensor and another section of the scanner shows a correct temp. So i think the scanner needs an update. I informed them of the issue, hopefully they can fix it.