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When I start the car, the needles on all the gauges do their "boot-up" but the temp gauge doesn't move after that. just started happening today. I have heat and coolent. But seems like the radiator fans run all the time. What happened? Any help appreciated. Thanks. It's the 2.4 engine. 2006 sedan 25k. Took a 150 mile cruise yesterday all was well. I believe it was working on the way to the grocery store today, but not when I came out. I searched the forum threads but didn't find anything conclusive. Wiggle the sensor wires helped someone but where are they located? No warning lights on. Thanks
 

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When I start the car, the needles on all the gauges do their "boot-up" but the temp gauge doesn't move after that. just started happening today. I have heat and coolent. But seems like the radiator fans run all the time. What happened? Any help appreciated. Thanks. It's the 2.4 engine. 2006 sedan 25k. Took a 150 mile cruise yesterday all was well. I believe it was working on the way to the grocery store today, but not when I came out. I searched the forum threads but didn't find anything conclusive. Wiggle the sensor wires helped someone but where are they located? No warning lights on. Thanks
I'm going to throw a random guess out and say it might be the engine coolant sensor. I'm not familiar with where it is, though. It's probably a good place to start -- it's not hard to replace and its cheap. Like you said, it could be the wires to the sensor - they could be not making good contact or there might be a broken wire.

Cheers,
Nick
 

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Discussion Starter #3
update:

Let her sit overnight and all was well in the morning! Go figure?? 3 days now no problem. These cars do wierd things at times. I had a power steering "lock" and restarted the car and it went away. Thanks for the reply.
 

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Did this come back to haunt you yet cause I'm having the same problem and my fuel mileage is horrible because the car doesn't know it's warmed up and the fans are full blast in the winter is probably not the best..
 

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my car does it sporadically. Especially on cold mornings. I replaced the sensor and sensor connecto....no change. Disconnect and reconnect of the battery terminal clears the problem, but thats annoying. I read somewhere it might be a thermostat problem that is making the car think it isnt warming up quick enough. Got one but havent replaced it yet.
 

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I am having the same issue with My 06 g6 sedan, it seems to be a common problem with the pontiacs from all i have been reading, next time it happens check your air conditioning to see if it is working, usually when the temp guage on the dash is not working the a/c follows suit, but the next time i started the car everything is ok. I have been told by a mechanic friend of mine it sounds like a ECU problem. since there are many of these doing this then i wonder if there are any lemon laws to protect buyers of this?

to add to this I have replaced the temp sensor on the back of the engine on the drivers side of the head, and that did not fix the problem. does anyone out there know of an alternate temp sensor on the car or is this the only one?
 

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I am having the same issue with My 06 g6 sedan, it seems to be a common problem with the pontiacs from all i have been reading, next time it happens check your air conditioning to see if it is working, usually when the temp guage on the dash is not working the a/c follows suit, but the next time i started the car everything is ok. I have been told by a mechanic friend of mine it sounds like a ECU problem. since there are many of these doing this then i wonder if there are any lemon laws to protect buyers of this?

to add to this I have replaced the temp sensor on the back of the engine on the drivers side of the head, and that did not fix the problem. does anyone out there know of an alternate temp sensor on the car or is this the only one?
To Update this I figured out the problem was the thermostat on the car, basically it is letting too much water flow thru the engine at all times and never allowing the engine to warm up properly, the computer realizes this and then throws a code up and goes into a "safety " mode just incase the temp sensor has gone out, and disables the ac and turns both fans on full blast first thing when you start up the car. so it could be the temp sensor in your car, but if you are electronically inclined then just take and ohm the sensor out, if you get infinite resistance then the coil is broken inside the sensor and the sensor is bad. if you get a reasonable resistance reading, then most likely the sensor is good and the thermostat just needs replacing, which is actually pretty easy on the 4 cylinder. it is to the right of the engine just down below the head and temp sensor. I am offshore right now so i will try and post pics of this when i get home. the thermostat was 22 bucks at autozone and about 10 bucks for a gallon of dex-cool pre-mixed coolant.
 

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I'm having the same problem. I replaced my thermostat not too long ago and my gauge isn't reading, the a/c stopped blowing cool air and my fans are constantly running. Should I take it to a mechanic? Any advice is much appreciated.
 

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I'm having the same problem. I replaced my thermostat not too long ago and my gauge isn't reading, the a/c stopped blowing cool air and my fans are constantly running. Should I take it to a mechanic? Any advice is much appreciated.
Probably your ECT sensor then. A scan tool will tell you. An ECT that is not reporting to the ECM will result in the ECM substituting a very low temp value (IIRC: minus 40 F).
 

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OK. I have a 07 with the 3.5 base sedan 79,000 miles. Mine started acting up about 6 months ago and this is what I have done to "try" and get this problem fixed. First, I replaced the Coolant Temp Sensor. Worked for a week or so and the temp gauge stopped working again. Of course everytime it stops working the engine goes into Safe mode and the fans come on and the A/C will not work. When it stopped working this time the CEL came on and I got it scanned at a local auto parts store and it came up as a bad sensor again. So, I figured, I must have purchased a bad sensor and I put another new sensor in it. Sure enough, another week later the temp gauge stopped working. No CEL this time though. So, reading thru the forums I found the thermostat might be the problem. Had a new thermostat put in and another week went by and the temp gauge stopped working again. After reading some more I saw where the radiator cap might be bad. I replaced that and all was good for another week. Talked to a friend of mine at the dealership and he said that the connector to the sensor goes bad all the time so I replaced the connector. Connector part if you need one is AC Delco part# PT1728. Sure enough the temp gauge started working and lasted 2 weeks this time. I got it working each time it failed by removing the negative cable from the battery for 10-20 seconds. I went to the dealership and asked them what they thought it might be and they wanted to bring it into the shop but it happened to be working at that time and I told them that I will bring it back once it fails again. It stopped working again this morning so I took it straight to them and they have it right now. Once I get it back from them, I will update and let everyone know what happened. Hopefully it will only need an ECM flash and that will fix it.
 

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OK. I have a 07 with the 3.5 base sedan 79,000 miles. Mine started acting up about 6 months ago and this is what I have done to "try" and get this problem fixed. First, I replaced the Coolant Temp Sensor. Worked for a week or so and the temp gauge stopped working again. Of course everytime it stops working the engine goes into Safe mode and the fans come on and the A/C will not work. When it stopped working this time the CEL came on and I got it scanned at a local auto parts store and it came up as a bad sensor again. So, I figured, I must have purchased a bad sensor and I put another new sensor in it. Sure enough, another week later the temp gauge stopped working. No CEL this time though. So, reading thru the forums I found the thermostat might be the problem. Had a new thermostat put in and another week went by and the temp gauge stopped working again. After reading some more I saw where the radiator cap might be bad. I replaced that and all was good for another week. Talked to a friend of mine at the dealership and he said that the connector to the sensor goes bad all the time so I replaced the connector. Connector part if you need one is AC Delco part# PT1728. Sure enough the temp gauge started working and lasted 2 weeks this time. I got it working each time it failed by removing the negative cable from the battery for 10-20 seconds. I went to the dealership and asked them what they thought it might be and they wanted to bring it into the shop but it happened to be working at that time and I told them that I will bring it back once it fails again. It stopped working again this morning so I took it straight to them and they have it right now. Once I get it back from them, I will update and let everyone know what happened. Hopefully it will only need an ECM flash and that will fix it.
I'm very interested in what solution finally works for you long-term.
 

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I got the car back from the dealership. Come to find out, the problem had nothing to do with the engine cooling system at all. Like I said before, there was not a CEL on. They hooked the car up to the Tech 2 and it gave them code P0116. The problem was actually the Mass Air Flow Sensor connector. $304.00 later and they replaced it and the car is running better than it ever has. I have been having some idling problems where it seems like it's running rough when I was stopped, but I figured that had something to do with whatever was making the engine run in safe mode. So, even though you may have a temp gauge that doesn't work, it could be something totally different that is causing it to go into the engine protection mode. I hope this will help out some of y'all in the future.
 

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The 116 code is for ECT sensor signal performance but if there was no MIL it was historical.

I'm wondering if the issue was with the MAF/IAT combi sensor harness/connector all along but then why no MAF or IAT sensor code?
 

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I believe you may be correct @Greenman. I may have been just chasing ghost's the entire time. So far it's still good to go though. But, with anything that is controlled by electronics, you never know what the problem is.
 

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yeah, if your temp gauge reads zero and the a/c wont turn on and the fans are on high its probably the thermostat. what usually happens is te rubber seal on the thermostat will go bad and tear and it will allow coolant to flow before it is suposed to at 185 degrees. I had that same problem and i just changed mine and it fixed it. i have the 3.5l and it was not that hard just very very little room to work with and if your going do it yourself get ready for a mess! Lol. It is located on the hose that goes from the bottom of the radiator to the bottom of the engine on the passenger side of the engine between the radiator and engine.
 
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