Chevy HHR Network - P0128 & c0460

Posted about a week ago. Didn't have all the specifics, here's the history.

Have a 2010 HHR with a little over 73000 miles on it. About a week and a half ago, the engine light, air bag light, service ESC lights/msg would come and go randomly. Both the analog temp gauge and the digital read out flatlined (---). The temp gauge would come back on, then go out again for a period of time, then return. I took it to a mechanic that I trust and they did the codes diagnostics thing and went about hunting down the issues. They said that it appeared that the modules were not communicating with each other. By virtue of unplugging/plugging all the modules and electrical connections, all the lights/msgs went off. I anticipated at a minimum that the thermostat would need replacement, they said no. They charged me $49 for the code diagnostic service and I had the passenger window switch replaced on the driver door since it would allow you to put the window up, but not down.

That lasted about 4 days and the sporadic temp gauge in/out returned, as did the engine light sporadically, as did the service ESC msg (the airbag light did not return). When the temp gauge is operational, analog it registers about 1/4 a few miles after starting, and rises to about 1/2 after a while on the road. The digital read out never goes above 170/180. I did have the brakes serviced about 6 weeks ago, with the front rotors being replaced. One of the tire pressure gauges (front driver) is out and I just haven't gotten around to getting that replaced. The last time I checked the time pressure, that front driver tire was down to 28, while the rest are around 35. I have checked the radiator and when you open the cap, it is full and the reservoir does have some fluid in it.

Anyhow, have had a beyond busy week ... today, it is colder in the Tampa Bay area. It was in the low 50s in the a.m. and humidity in the 40s (stop laughing, that's cold for us thin blooded Floridians. People near the Gulf waterfront are wearing winter coats. HHR is use to running in 90 degree temps and humidity higher than that) ... during a 15 mile drive, car stalled out about 5 times when you begin to go again after stopping for a red light ... it just sort of chokes/idle drops, but restarts and goes immediately. Did make it to Autozone today and had them do the codes diagnostics and they have come up with P0128 "coolant thermostat temp below thermostat regular temp" and C0460 "steering position sensor calibrated data set not programmed". The temp gauge was flatlined this a.m., but kicked in after about driving 20 miles and registered at 170. And after driving about 15 miles and the temp warming into the low 60s outdoors, the stalling stopped.

Any comments, suggestions ... point me in the right direction. I'm going to check the tire pressure and add if necessary.

Thanks in advance.