is the sensor gone bad and where is it located on my 2006 hhr 2.2 litre and is it difficult to change all other gauges working fine thanks for your help douglas:

 

Under the front bumper cover Right side on the frame horn.

If you try a search I know someone has posted the picture a few times. Try this one:
https://www.chevyhhr.net/forums/prob...-sensor-54418/

 

If you want to know what the actual outside temperature is, purchase an aftermarket unit that might actually work. GM had very good external thermometers for years but they screwed up badly on the system used in the HHR. They have a technical service bulletin that basically says that anything it does is normal. Mine will stick on one temperature sometimes for as long as a week then work for a few months. I've taken it out of my garage on a below 0 day, driven 30 miles at 65 mph and it stays at 45 degrees. I assume the problem is in the software. Disconnecting the battery might reboot the program.

 

Both of mine have been very accurate. 2008 under the bumper cover, 2011 inside the grill area.

 

My 2007 works just fine!