[i007spectre]

Originally Posted by ex-boxing champ

I'm more confused than ever now. So should I replace the sensor or the thermostat?

Same boat man. No idea where to start.

[arpad_m]

Here is my amateur understanding of the functionality these two parts provide.

The thermostat governs the opening and closing of the valve that enables coolant flow. When it works, it opens and closes regularly to keep coolant/engine temperatures stable and in the optimal range. When it gets stuck open, the engine is always cooled and takes much longer to heat up; when it gets stuck closed, the engine can overheat because coolant isn't flowing. Either way, coolant/engine temperature should display correctly.

The temperature sensor is usually very close to or part of the thermostat and sends a temperature signal to the BCM that then displays it in the cluster. When it fails, the display is stuck at a single temperature, usually 0. This does not necessarily mean the thermostat is broken, just that you have no indication of actual temperatures.


EDIT: this is what I found in the service manual about thermostat housing replacement for the V6 engine (LGX), not sure if it's enough for you guys, but hopefully it's a start.

[UnknownJinX]

The constantly running fan is a failsafe feature that the ECU will engage when it detects something wrong. You might also notice that your oil pressure is higher than normal as well.

arpad pretty much covered everything. I would say that you could just idle the car for more than 10 minutes, open the hood and feel if the block and the upper radiator hose are lukewarm, but now that the weather is cold, I am not sure if this works well. If they are still pretty much cold after idling for a while then yeah, you have a stuck open thermostat.

I once helped a friend flush his NA Miata's coolant and found that the block would be pretty hot but the radiator is still stone cold and this is after idling for 10+ minutes on a summer day. Turns out the thermostat is stuck closed. Ended up helping him replace the thermostat.

If it's failing to pick up anything then yes, that's the coolant temperature sensor. Get an OBD2 reader and you should know what's going on.

[i007spectre]

Well either way thankfully im better off, or at least will have an easier time, than the OP simply because I have the V8.

[The Maverick]

Originally Posted by i007spectre

Well either way thankfully im better off, or at least will have an easier time, than the OP simply because I have the V8.

Yeah, finding out the intake manifold has to come off to replace a thermostat was an unpleasant surprise about the V6!

[i007spectre]

Only thing that would make it easier would be not needing to empty coolant first.

[ex-boxing champ]

Ok I bought a ODM2 meter and it says I need to replace the thermostat. What kind of tools will I need to get this job done and realistically how long should this take? Would you guys recommend me buying the part and then paying a mechanic to do the work? The biggest car project I've ever done is replacing bad brake pads and this was 15 years ago.

[dpevans]

Originally Posted by ex-boxing champ

Ok I bought a ODM2 meter and it says I need to replace the thermostat. What kind of tools will I need to get this job done and realistically how long should this take? Would you guys recommend me buying the part and then paying a mechanic to do the work? The biggest car project I've ever done is replacing bad brake pads and this was 15 years ago.

You mean you bought a OBD2 scanner? Not sure how it tells you the thermostat is stuck. If your coolant temperature is not registering on your dash that is an electronic function controlled by the coolant sensor not the thermostat. The thermostat is a mechanical device so when the car is cold it stays closed to warm the engine quicker and when the engine reaches the operating range of the thermostat it opens and sends coolant to the radiator to cool. If the thermostat fails closed your engine would be overheating if it fails open it would take forever for it to warm up. Someone already mentioned the fans staying on is an electrical fail safe controlled by the ECM. I would suggest you watch a youtube video on replacing the sensor and the thermostat then you decide if you are up for the job. DIY Yardie has a great video on changing the sensor. It's a job I would do myself but you might be exceeding your comfort level pulling the intake and having the right tools to get the sensor out. Good luck.

[STEVE41]

Originally Posted by dpevans

Even if the thermostat failed your dash would read the engine temperature. .

it won't, u will see once the op reports back after it is fix

[STEVE41]

Originally Posted by ex-boxing champ

I'm more confused than ever now. So should I replace the sensor or the thermostat?

you are wasting your time and money, it is your thermostat. Period. i replaced too many to know. do the sensor if that make you happy but you will find out that wont fix your problem.

[S.Macias]

For what it's worth..

[STEVE41]

Originally Posted by S.Macias

For what it's worth..

bingo!!!

[Racereddie]

Originally Posted by ex-boxing champ

I'm more confused than ever now. So should I replace the sensor or the thermostat?

[i007spectre]

Ever since the last time I disconnected the battery the car will tell me which seat memory setting I am using on the dic at startup. It never used to before.