Again, the standard elm327 type code reader(like most auto parts stores use) cannot read transmission codes.

What device was used to check the codes?

 

My code reader is pretty much a generic reader that I have had for years, not real detailed, but has been good for basic code id and clearing stored codes. I will take a look at the grounds to see if that can help. I pretty much have always done my own repairs, but do not have the right scan equipment to do a detailed diagnosis, I know once I can get it diagnosed, I should be able to repair it myself. . I don't want to start throwing parts at it, as with the newer cars, one almost has to take it to a reputable repair shop that can do the diagnosis . I am going to play around with some things in the next couple of days to see if I can identify any issues, and from there will take it to a shop I know that is a very honest tech, that I feel should be able to tell me what the issue is. The car runs and shifts great, and exhibits no other real problems other than the fluctuation of temp readings, and no overdrive. I do thank everyone that has given me some good things to check out, I have found that forums are one of the best sources of info out there, and the members are great people!

 

I had bought a 2008 HHR a couple years ago and the transmission would shift bad while it was cold. It turned out to be one of the shift solenoids. I changed the 1-2 shift solenoid, 2-3 shift solenoid and the Torque converter solenoid. Drained the trans fluid, changed the trans filter and refilled with that expensive synthetic trans fluid. Has run perfect ever since. The burned solenoid was obvious once I removed it and inspoected it.

 

Well, took it to a friends repair shop, and he found an additional code of p0751 in addition to the p0700 which indicated a bad 1-2 shift solenoid. He went ahead and replaced both solenoids, changed the fluid. It fixed the problem with the overdrive, runs great again. The DIC coolant temp display still seems to fluctuate like it did before, maybe this is normal, I never really monitored it consistently like I have recently. The temp gauge seems to be unaffected, shows normal reading. If someone out there could monitor their DIC coolant temp and let me know if they might see something similar, I would really like to know. But I am again, happy with my HHR!

 

Glad it's fixed! Yes, fluctuations in coolant temps are normal. As RPMs increase, the water pump moves more coolant. As vehicle speed increases, more air moves through the radiator. Both of these reduce coolant temps .

 

Don't expect the analog gauge to be in any way responsive... It's closer to a cold/normal/too hot gauge.