2001 alero.


The temperature guage is stuck at c. Won't budge at all.


Notice that a few seconds after I turn on the car the radiator fans kick in and won't turn off.


I ran to autozone and bought a new coolant temperature sensor, but that didn't do the trick.


Did notice that originally the coolant had been getting low in the reservoir tank. Not sure if this was an issue.


So anyway, does anyone have any insight on what would cause these issues to trigger simultaneous? Any help would be great.

First, which engine is this?

Second, has the car been scanned for codes?

3.4, 6 cylinder. Yea, I did get a trouble shooting code of: P0128.

Just how low is the coolant in the reservoir? If it ran dry you could have air in your cooling system, which could cause the problems you are seeing. I would confirm any air has been purged out of the cooling system, and possibly replace the thermostat (a failed thermostat could also cause your problems). This cooling loss has me concerned as it might be signs of a bigger problem. Look on the dipstick for any indication of water in the oil (foaming) and look in the coolant reservoir for any signs of oil in the coolant. Fill the reservoir to the proper level, and monitor the level on a regular basis to see what happens.

Will check about air in the system when I can get back at the car this afternoon. Purge. The dipstick is okay, no head gasket leak internally from that. The coolant was getting pretty low but it was so hard for me to tell because the reservoir is so opaque can't see.


Now would a stuck thermostat cause the fans to kick in instantly like that?


AC is off as is the front defrost. However, my wife (this is her car) said that the rear defrost wasn't working of late. Not sure if coicidense or a factor.

Well, the rear defroster has nothing to do with this......that is a separate issue....

Your reservoir was low....but how low? I don't think you have a radiator cap, you just have the reservoir cap?

P0128 is usually a bad thermostat, or there is a problem with the coolant sensor circuit....bad sensor, open circuit, or bad PCM.....rare for a PCM in this case.......

If coolant was low, you should fill to cold level and with the reservoir cap off, run the vehicle....if level drops, add coolant to cold level.....if level starts to rise above the cold level, reinstall cap.....

An air pocket will not keep the sensor level cold, if anything, it will cause it to overheat, and your gage should rise.....

Since you replaced the coolant temp sensor already, i would go to a place like AutoZone...have them see if P0128 is still there, and also check, the coolant data.....if data is reading, -30F, then you have an open circuit in the coolant sensor harness.....if it is reading a number under 100F, then I would definitely replace the thermostat, and burp the system....

Okay Got it, I believe. The temperature gauge works again, and now the fan doesn't kick in until the needle is somewhat above the halfway point.


When I took it into autozone the guy there cleared out the codes (I had thought that if you unhooked the battery for a couple hours then afterwards drove it around that reset everything) then spent quite a while getting the air out of the system.


Now I'll monitor and make sure that I'm not loosing fluid.


Want to thank everyone for the help.

So, did you put a new thermostat on, or was the only change to bleed all the air out of the cooling system? I still think the problem was related to loss of coolant ... to the point where the reservoir went dry and air got into the system. My main concern is what is causing the coolant loss.

No thermostat. Changed the ect sensor (which in retrospect was probably unnecessary) and then got the air out.


You're right about what was causing the coolant loss to begin with. Will have to monitor.

Spoke too soon.


Been driving the car for a week and not out of the blue we're back to where we started from. The needle is back to not moving. The fan kicks in after you start the car. The coolant seems fine though so I'm at a loss.