Mine just did this again, be going in to the dealer this week.

 

Well, they replaced the thermostat. Hope this does it.

Strange thing is, let me know if this is normal, I've been smelling something like when I had cars in the past overheat. Could this be the result of a sloppy job pouring and the excess is now burnming off?

 

I know this has been said to be a myth, but have you guys checked to ensure all the relays are pushed in all the way. I didn't have any issues but I did have a couple relays move alot when I checked mine for the first time at about 30,000mi. Just a thought. I really don't think it could be a thermostat, did either of you notice how quickly or slowly the gauge dropped? If it just slowly fell to the bottom it might be the thermostat, but if it just fell like when the car turns off then it has to be electrical.

 

Ive been lurking around here for some time, sorry for the lack of an introduction post. I'm not a 'real mechanic' but having spent two years in college for an AAS degree (in cars) I believe I know what you're issue is, and your guess was pretty good as well. If it flatlines to zero degrees your issue would not be your thermostat. You can remove your thermostat from the vehicle and will still get a reading above zero.

Zero degrees is (or was on the older gm cars) recognized by the PCM as a zero volt reading. Check the wiring or replace the temp sensing unit. It should be in the block somewhere reading the temp of the coolant. Chances are you'll have to lower the coolant level.

And it will fire off a trouble code as a zero volt reading is read by the engine as -40 degrees (or -70, i cannot remember) but the car compares that reading with the rest of the readings (intake air temp for one) and can determine which sensor is giving the bad readings. I would think that once it goes out its out for good so maybe the wiring is lose, or there is dirt in the connection somewhere. Check that out if you have a voltmeter you'll be in good shape.

Hope this helps.

**Off topic** I do plan on actually posting more and buying a HHR... hopefully a Victory Red SS will be in my driveway next year.

Cheers!

 

Welcome Shefz28. Anyways, good to receive info and the more we get the more we can help one another with problems, and where to get items also. Since you have been lurking for some time, that much mean you like the site.

 

ShefZ28....

First welcome to this forum. Your involvement will always be appreciated.

Your diagnosis is also in my way of thinking. I have operated vehicles with thermostats removed, and always had SOME indication (movement), of a temperature reading, on an analog gauge. So I am in belief the thermostat is NOT the problem. Still sounds more on the electrical side to me.

For those who have had the analog display zero out, did you check the DIC reading at that time??? Or did "everything" go out??

 

I don't disagree with what you guys are saying.

All I know is I took it in and that's what they fixed. At least now it's on record as having the problem. didn't cost me anything but some time. if it happens again, I'll go back. If not, even better.

 

One thing that us "old farts" need to keep in mind is that modern cars don't just have a sending unit connected directly to a gage anymore. The signal goes through the computer now.

The Diagnostic Trouble Code (DTC) for a stuck open thermostat is P0128 for "Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature". Many auto parts stores will pull codes at no charge (Autozone does it in my area).

A friend and member here just went through this on his HHR. No readings, MIL. The dealer messed up the first visit and reflashed the ECM per a TSB and code update for sensitivity range, but that pertained to the 2.2, not the 2.4, which his was. The second trip, the thermostat was replaced and all is fine now.

 

I'm in agreement with you Joe.

But I think someone, I believe oneton, mentioned the HHR has 2 sending units. That has me wondering, and why I asked the question, of the possibility of the DIC temperature working correctly at the time the analog gauge is "bottomed out". I would think if that indicator is displaying the normal temperatures usually experienced, the thermostat is not at fault (but, it could be blanked .....- - -... out, as well).

Now, I do admit that I have no idea what the 2 different temp. sensors are for. I'm just trying to use some rationale (effective or not) and try to help resolve somebodys problem.

 

Wow, I'm thoroughly impressed with the knowledge that abounds these pages! And yes, both gages do go immediately to flatline and the car is heating normally, (saying that from 30 degree mornings here). Mine is still in and out of registering a temperature and the check engine light seems to accompany those spasms. I just can't bring myself to dump nearly 400 clams into the dealer for something so trivial. Where are the 2 sending units mentioned in here? I can assume 1 is block-side, but the other seems like a waste, but that's what keeps us "old farts" from working on the damn things! So for you guys that had the thermostat replaced, is that truely what was done or did the dealer merely check/fix loose relays and send you on your way. Or did they soak you for replacement costs (if out of warranty) and do the relay thing as well? Can't help but wonder............