If you have a VOM, I would remove the temp sensor and check resistance values as best as you can at the following temperatures:
0 (farenheight) 14,650 ohms
19 ........... 8,100 ohms
39 ........... 4,780 ohms
70 ........... 2,350 ohms
100.......... 1,250 ohms
160.......... 400 ohms
210.......... 190 ohms
If out of spec....replace
If not, Lookk closer at wiring....maybe bad ECU??
Hope this helps!