why is my temp gauge spiking up and down with megasquirt

[daveeclipse99]

i have had megasquirt ecu in my 420a for a while . now my car wont start and the coolant temp sensor gauge is spiking for -40 to 150 degrees on my laptop! is it a bad sensor ? or do i need to calibrate the sensor again ? please help

 

[viprez586]

Sounds like a bad sensor if it's making your car would not start. That would mean the thermo sensor has open circuit(ed).
I'd replace it - a new one will be more accurate anyway.