Thanks for the input guys! I'm hesitant to drive the car any more than I have to (to pull the codes)...I've been running around on the motorcycle picking up parts all day. The light's been on for a while because of an O2 sensor issue...replaced the sensors and the light still came back on, I'm guessing I need to replace the cat too...again. Anyway, I do need to pull the codes again to make sure that other codes didn't get triggered, but I don't want to really drive it until I get this thing sorted. I know that sorta cripples me, but there I am. lol

I'm going to try changing the coolant temp sensor, since it's right on the thermostat housing but I actually don't have to remove anything to get at it. lol I need to bleed the system, but the coolant level in the rad and reservoir were normal. I'm thinking that if the temp sensor was working properly, whether the thermostat was stuck open or closed the temp gauge would read SOMETHING in city driving, even if it was abnormally low or high. This thing doesn't budge from where it is when you first start the car. If that doesn't work, I'll go about swapping the thermostat...crossing my fingers. lol

 

Did you replace the cat or the whole downpipe?

 

Just the cat, I would assume. I had a shop do it. I don't have access to level ground and jack stands. lol

 

Just to update the thread, the problem I was having was the ECT sensor. Was a very quick fix, and the part was $14 at Advance Auto. I'm just glad I didn't have to pull off the throttlebody. lol

 

Hey dragknt is that exactly what that part is called? I have replaced the coolant temp sensor, the thermostat, and checked all the levels to no avail. My 2000 Monte Carlo still does the same thing gauge not working and fans on all the time. Where is that located?

 

Sorry i figured out that what i replace was the ECT sensor sorry.

 

You do know that changing a thermostat on a 3400 shouldn't take more than 45 minutes, right?

First, remove anything blocking access to the thermostat (diagonal brace, factory air filter/intake assembly, upper rad hose, etc.). You shouldn't have to remove the throttle body! Use a long crescent wrench to loosen both thermostat housing bolts. Remove the front bolt completely and only loosen the rear bolt enough to lift the thermostat housing up and away from the engine. Pull it towards the front of the vehicle, and it should slide off. (The rear mounting hole is "slotted" specifically for this purpose). Due to the thermostat being sideways, you may need to use a flat-head screwdriver to hold it in place so it doesn't drop and bind up against the housing as you attempt to remove it. That's the hardest part. Once it's off, getting the new one in is easy. Installation is the reverse of removal.

 

i have a 2006 monte carlo LT
I noticed today that my temp gauge is not working it was working before.
The temp gauge would come up about half way I would have heat.
Tonight after work I was driving home I got the message ENGINE HOT A/C OFF
I had heat in the car but the temp gauge was at the bottom.
I would like to know why I got the message tonight but I still had heat
I dont want to have my car overheat I need it to get to work

 

5 hours to replace the thermostat is about right. The thermostat housing bolts are between the intake and exhaust manifolds and under what I understand to be the throttle body, right? I was wanting to ask someone with experience if I need to apply gasket maker to the thermostat housing or will the gasket on the thermostat itself be all that it needs in order to make the seal water tight. I'm hoping someone could please give me a reply because I just installed the it like that without using anything else besides the seal that is on the thermostat itself and I really would like to proceed with confidence that I done the work properly. I am replacing it because I failed the inspection because ,even though my check engine light was not on, it threw three codes1.)P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL
2.)P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD 3.) P0442 SYSTEM LEAK DETECTED
(small leak). I had noticed about a month or so ago that the heater wasn't working even though the guage read one quarter and the heater will usually be warm enough before it reads at all. Anyway, that lead me to believe that I have a thermostat issue. As far as the other code I believe my gas cap could be loose causing it to fail. Of course these are all guesses and I was thinking that after I change the thermostat and get the air out off the system I would take the battery loose for ten minutes. I am under the impression that will reset the codes and, Lord willing, I will pass the inspection next time if I'm right. If an experienced mechanic happens to read my post and find any errors in my understanding of what's going on, please by all means, let me know what you think I should do instead. Thank you for your input

 

I have confronted the similar problem as you before.