my 95 850na has always ran regularly, with the temp just barely above the horizantal point. but recently with the cold weather (reads 0c, at highway speeds drops sometimes), my temp reading drops significantly when cruising at highway speeds. the heat also stops heating.

Im just wondering if this indicates an issue with the temp sensor, or thermostat, or both?

 

my guess is your thermostat is stuck open

 

+1 Thermo stuck open

 

+1 on t-stat, I would replace the ECT sensor alone with t-stat.

 

yea usually id change the sensor, but im broke as a joke lately, pretty sure its operating fine tho

 

Evidence that it's operating fine? Because I'm with the T-stat guys above.

 

when the car was reading cold at highway speeds, the heat was also blowing cold. After replacing the t-stat the car runs consistently at running temp once warmed up, warms up quicker also

 

T-stat is cheaper, also the most likely problem.

 

Does it still run colder at highway speeds after you've replaced the t-stat?

 

oh yea, it warms up no prob and stays there once at running temp. when i removed the old t-stat i immediatly noticed the part that closed was on an angle, so it would never fully close

 

Sounds like I'll be doing this as well. I sick of the cardboard packed in front of my radiator so i can get heat. lol
Kinda ticks me off, i just replaced the the Temp gauge, and the Tstat was done 12k miles ago.