So I just bought my HHR a few weeks ago. I noticed today the thermometer showing the temperature outside the vehicle wasn't working properly. It was well over 90 degrees all day today but the display read 74. Any ideas on if this is a quick fix or how much it would run me if it's not???

 

were you driving around, or just checking the temp with your car parked? If you dont move around, the temps will be off.

 

both while driving and sitting parked.

 

not sure on a quick fix but the sensor is located behind the passenger side fog lamp/wheel well. I have heard that the high pressure car washes can hurt it with the undercar wash. hopefully someone else can chime in

 

It takes mine about 20 min. of driving before it picks up a temp change

 

You are aware of the quirky programming the sensors have on the HHR. Don't know if anyone is exactly sure what the algorithm is. You have to drive a set time,speed and distance before it will display an updated temp.
I know mine has to go about 6 miles before it reads correct.
Maybe yours isn't broken but just hasn't met the algorithm values.
Lots of folks have complained about theirs not working, only to find out it is working as designed (stupid design I might add).

 

I believe its 18 MPH or greater for a minimum of 15 minutes. If you drop below that magic 18MPH, after driving for 10 minutes above, your back to 18MPH for another fifteen minutes. Yes I agree its a stupid design. I have other non GM vehicles that behave better IMO. If the temperature is lower than displayed it will begin to decrement almost immediately, but not true if the temps are higher than displayed.

 

Thanks so much to everyone for their help. I think the thing regarding an algorithm is true, because I made sure I drove it about 20 minutes straight today and it finally changed the reading to the correct temperature. So I guess that was the issue. I'm still new to my HHR and have many friends with built in thermometers for outside temp that seem to work a lot sooner, which is why I was so worried.

 

Yes TEKNOnaut, it is a silly design by the engineers.
I have a Dodge truck that gives an instant reading when you start it. Problem is I've seen it read 114(mid 90's actual air) if it has been sitting in the hot sun. It will start coming down with the airflow through the grill.
Neither design is perfect, but I feel the GM engineers took the HHR specs to the extreme.

 

My 2008 LT seems to give good readings immediately upon starting the engine, sometimes it seems high but I think that is due to the lack of air moving around it.