I did a search and found one reference but not much discussion. We live in Tucson so there are not many cold mornings, but twice this season the check engine light has come on when outside temp is low 30s. Engine runs fine, no overheating noted. When outside temp is warmer the check engine light does not come on. It had only happened once before today so I have not taken it anywhere to capture any codes. Any educated guesses on what is going on?

 

Probably not heating up fast enough. But without the code.......

 

I agree with donbrew that the "not heating up fast enough" may be the cause.
You may have a partially bad thermostat that is letting a little coolant bypass through when it is cold.
Since the car is about 5 years old and needs the coolant changed, might as well put in a new
thermostat also.

You've been a member here long enough to know. If you have a CEL, always post the code number when looking for help.

 

I will get the code read and update. Coolant flushed and changed one year ago, about 6000 miles since then. This is a 2006. Thanks.

 

Thought we were talking about your 2010. Oh well, same suggestions apply.

Fwiw. Here is a good example of posting questions on this forum. Always include the year, engine and mileage when looking for help. They are NOT all the same. Also include any CEL trouble code numbers.
I know this sounds like a broken record but you wouldn't go to a doctor and just say "I feel bad. What's wrong with me".

 

Coolant was flushed and changed last year but how about the T-stat?
Was it changed and if it was did you replace with an AC Delco?
Some aftermarket brands open to late or early and the computer sets a code

 

This forum rocks. My 2006 2.4 HHR (67K miles) had the check engine light come on about 2 weeks ago. Pulled the codes today and they are the P0013/P0014. As it happens, it started shifting really hard from first to second today. So I will be using the information from the how to thread to replace both the exhaust and intake solenoids. I read all 52 pages in the tutorial but has anyone else heard a clunk when shifting from Park to Reverse or Park to Drive with this condition? That was the first noticeable symptom other than the check engine light and was followed by the hard shifting. After arriving home and starting it again later, there was no clunk between Park and Drive and no hard shifting.

 

This thread continues at the tail end of https://www.chevyhhr.net/forums/how-...52/#post768785

This thread is closed now tucsondivots has found the "fix" - now go get your hands dirty man