Coolant temp always low.

Heat works good coolant is topped off with yellow antifreeze tested to -35 -40 what could be the issue?

 

What does your temp gauge show after engine warms up. Probably a coolant sensor. What year model and engine? 97 and 98 have 2 coolant sensors

 

ehh a little below half way and its a 03 SuperCrew 5.4

 

How do I turn the service engine soon light off? Haha sorry I've never had it on before.

 

Stop by a shop or go to autozone or oriley and ask them to read codes. You can look on the scanner ans hold down the button where it says "Erase."

 

that's what I did I figured it was just the cold weather messing with it

 

I have the same year and model as yours. Driving home from out of town last night mine popped on with the same code. Mines also showing about the middle part between half and the bottom. I reset the code seeing if it comes back. I figured its the cold weather we are in right now.

 

Right for 97/98, one coolant one head. ECT and CHT sensors. The ECT is a wet socket, - CHT is a dry socket (no contact).

The brass bulb of the ECT can get corroded over time. Might be making it flaky.

I'd reset the KAM, see if it comes back before doing anything here.

You can pull the PCM fuse to turn off the CEL(MIL) to erase the KAM (KeepAliveMemory) or, - disconnect the battery (neg first then pos), touch neg and pos cables together, then reconnect (pos first then neg) or, - use a scanner if you have one.

You can also just disconnect the neg on the battery for a 1/2 hr or so, - that'll do it as well.

 

Bad CHT.

 

cht? Where is it? Difficult to change?