My ScanGauge2 is showing my IAT constantly at -40F. I just installed a brand new IAT sensor, with no change. Since it's reading -40f constantly, is that an indication that it has a bad ground wire?

 

I have the IAT sensor trouble code showing until I can get this fixed.

 

Thanks!

No. The signal is shorted to ground which produces the -40°F. When the signal is open and no ground present then the value will be 240°F. Being grounding the signal wire will drop to 0V (-40°F) and open signal will be +5V (240°F)

I lucked out on this. Previous owner had messed with the sensor connector and the positive wire pin wasn't contacting the sensor pin. 

 

I ended up cutting both wires so that the pins could lock into the connector, and then I connected them back to the two wires. Now my IAT sensor is working correctly again.