2003 Envoy Temperature Guage Sticks

I have had intermittent problems with the outside temperature reading getting 'frozen' into a number and staying that way for a day or so. At first, I could take the car on the freeway and get it above 65 MPH, and it would start working correctly. Now it doesn't seem to do that. I took it to the dealer and they replaced the sensor but that didn't fix the problem. I asked the dealer to call GM to try to isolate it. My own technical background tells me that the problem is likely in the firmware of the control unit. Either that or the control unit will continue to have intermittent bad readings until it fails. And I'm afraid that the control unit controls more than the termperature display so I want the dealer to do a little research before I leave it with them for a day. They don't want to do research. So I thought I would try here.

I had the same problem with my 03 Trailblazer. They first replaced the head unit but that didn't work. They then re-set the eprom, but that didn't work. The last thing they did was have the GM tech's on the phone because they couldn't get it fixed. Finally, the reset the eprom again and it hasn't acted up yet. (They did stress to me that the car has to be going at least 20 mph for something like 5 minutes or so before the temp will adjust.) Because mine was stuck for days like yours, this was not the problem. But, they finally did get it working again.

Good luck.
03LTZ