For the last ohh 5days or so when it started to get freakin cold, my truck would only warm up to about 120 degress, not even near normal operating temps of 195. I figured it was just because it was cold. Well now that its warmed up to 50, It still does not get near 195 degrees. I remember few short weeks it would warm up to 195 when it was 35 degrees out but now, not so much. I can def tell my gas is suffering and the engine does not sound the same.....Could it be stuck in open loop? It's getting warm just not near 195 and It'll stay like that for hours while I drive. ( just took a 2 hour trip )

 

Your thermostat could be stuck open. Staying in open loop wouldn't cause it to not get up to operating temperature.

 

Thanks, thats pretty much what I was thinking, just wanted some ones opinion before I go tearing out the old thermostat.

 

It could also be a bad sending unit. Mine died not to long ago and it would spike to 280* then back down to 195* in a matter of a few seconds

 

Thermostat was pretty much stuck open. For a little bit while I drove today it would start to heat up but fell right back down. Might as well change out the sending unit as well. Wouldnt hurt anything.