Temp Gauge Not Working [Archive] - GrandAmGT.com Forum


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09-16-2009, 11:13 AM
Hello again all! 2001 V6 GT here. I have had the following problem for about the last year and a half and just haven't messed with it as I know it's probably a sensor or something not to important. For the last year and a half my car will be fine for a few months then all of the sudden my temp gauge will just not work and my service engine light will come on. This will continue for a few weeks or a month at most then all the sudden it will just start working fine again. I took it up to autozone the other day and had an ODB hooked up to it and it spit out code P0125 and the guy there told me to replace my coolant temperature sensor, which I did, but I still have the problem. My car is not low on coolant, I could see coolant in the engine block when I pulled the sensor out and the coolant resorvoir is not only new but full as well, nor has my car ever overheated. Sometimes the low coolant light will come on briefly while this is all going on, but a quick restart of the car resets the low coolant light.

The most recent time this happened was just the other night, I drove 20 mins to a bar, the car was fine all the way there and up to the point that I parked and turned the car off. I was inside for a little over and hour, came back out and started the car and BAM service engine light on and temp gauge not working. I read this code could also be the thermostat? Anyone have an thoughts on what way I should go to resolve this problem next?

Also, just a side note. 3 weeks ago I drove from Vegas To Atlanta, 2,034 miles and not one problem, the temp gauge worked fine all the way and had no service lights on the whole way. This most recent incident happened about 4 or 5 days ago while I was up in Indiana and I drove all the way from Indiana back to Atlanta with the temp gauge not working and the service engine light on.

09-16-2009, 12:05 PM
The fact that it sometimes works and sometimes doesnt would indicate a problem with the 'circuit' and not the actual sensor. Im betting that you have a ground fault that is killing the readout on the sensor and setting the SES light.

Basically, check the wires to the sensor for any knicks, cuts, or abrasions and make sure the plug for the sensor does not have any wires that are loose or coming out of the plug.

The low coolant light is probably completely unrelated as sometimes the float in the reservoir will get stuck. A few taps on the side of the tank will usually free it up so that it reads properly.

Lastly, on the front (as you face the bumper) you will see a long black tube. At the left of that tube is a 3" tall tower with a small brass screw on it. Loosen up that screw and make sure you dont have any air bubbles trapped in the system. If there is air it will hiss out and coolant will begin to flow. At this point you can tighten the screw back down and youll have no more air causing problems.

09-16-2009, 12:21 PM
I was thinking more along the lines of the thermostat as after thinking back over time as to the times that the problem has occured it seems to only occur after the car has been started and possibly started after it has already been ran within the hour prior. I don't recall ever seeing the problem happen as I'm driving. At first I thought it might be a lose connection, but would probably see this happen more frequently and more likely while I'm driving, but don't recall the light and the gauge to have ever just stopped working in the middle of driving. I was going to attempt to trace the 2 wires out, but realized it would require alot of things to be removed as the wires appear to run up under the top portion of the engine.

09-16-2009, 04:28 PM
Well, its a relatively cheap part thats a PITA to change. Just make sure youre up for the task of changing it so you dont get partway through and end up not being able to finish. Im not sure how long it would take to just do that as every time Ive helped someone with the LIM gasket weve done the thermostat while everything is out of the way.

09-18-2009, 07:02 AM
Well I got the new thermostat, but it's been raining to much here to put it in. When I went up to autozone the other day I had them re-hook up the ODB and it seems now that my car is spitting out code P0128. I looked this code up and it seems very similar to code P0125 with the exception that it makes mention of my cooling fans. I have noticed now that both my cooling fans kick on within 10 seconds of the car being started cold and they run the entire time the car is on. Could this all be in relation? Anyone got any other thoughts before I go into the pain of replacing the thermostat?

09-18-2009, 09:58 PM
I don't know but just to give you an idea of how long the thermostat change will take, it took me about 45 minutes and that was going pretty slow just figuring it all out, I did however have access to any tool I needed, and I will say that unless you want to take the exhaust manifold off, it will REALLY help to have an open ended crescent wrench shaped in an S shape. Not sure what that's called, but I think you need it in a 10mm as a socket won't fit in there to take the thermostat housing off. I know it saved me a lot of time.