Transmission issues...
 

First off brand new here and thanks for allowing me to join and increase my knowledge in this HHR.
Name is Matthew but I answer to many things. That being said let's get to the point. I've done some reading in here but nothing seems to stand out to me besides, checking fluid levels and maybe changing the filter and gasket.
My 06 HHR has been having issues off and on with hard shifting into gear while stopped and while driving it does off and on not hard but you can tell it's not a smooth shift. My kid left work the other day and this problem happened to him, Car sat over night and I drove this morning issue still there. Let the car sit for about 2 hours and went to town to have codes checked, with ZERO issues. But I did park and shift in this order after the 1st drive with issues. Brake petal held in shift from D to N and pulled E Brake up, released brake petal, then shift from N to P. Again no issues after I've done this. Codes were the following- P0455, P0010 and P0300. Now Maybe I'm just dumb but with what the codes tell me I see Not how any of these would affect the trans. There is absolutely no feeling of misfire let alone multiple ones-P0300 . Everything drives just fine even when the trans does act up, so really lost on these codes showing anything. Recently I have taking a few long trips. Twice to upstate VA roughly 1,200 miles total and 1 to FL roughly 1,100 miles. I'm in Upstate SC. I don't have much money, I'm not working atm due to a medical issue and my wife is the only income besides my kids which isn't much. I can't go to shops, But I can try to do anything even if it's only in an hour spurt and I have access to good videos and breakdown drawings. A friend has a shop with a lift who could help me as he works on Tangs and Honda's. Any and all help and expertise would be greatly appreciated. I have 3 kids and 2 work. I'm scared to let them drive it. Which means we're down to 1 vehicle and everybody knows that can't happen for long. Look forward to hearing from you all and continuing be a part of this community.

I assume you have a 2.4L engine?
if so,
P0010 means you need new VVT valves, this causes hard shifting because the TCM goes into open loop. Very easy fix.
P0455 means there is a large leak in the EVAP system, most common cause is the gas cap seal is bad.
P0300 does not mean "multiple" or "random"misfires; it means unidentified misfire. Original spark plugs are good for 100,000 miles, have yours been changed on time with the correct plugs? Use ONLY ACDelco 41-103 plugs.

Don, Thanks for getting back with so fast it was greatly appreciated. P0010 VVT I'll check into on here. Although I maybe dumb I don't get how motor problems convert to Trans problems? But I'm learning and my ears are open as I do understand this motor is crazy IMO.
P0455 I know my son got gas before this happened. So I'll check that easily. P0300 I know the plugs and wires were changed by dealer when I bought it 5 years ago and have not since, put on about 70k since. I had check light and TC come on both times leaving VA with both times being something with a TB sensor or something , no hard shifting at all. I thought easy change and found out have to replace the entire TB as it is 1 unit at a cost of $500 bucks...JAW DROP!!!!! I also noticed it didn't do it unless using cc and accl button on cc. No issues on TB since I stopped using Accl button on cc. I will post when I go out and check over these things bit more here shortly.

I don't know where you shop but $550 is way high for a TB. I doubt that is the problem.

This is just the first raw search on ebay: https://www.ebay.com/itm/Throttle-Bo...AAAOSw0LVdFBP1

That price was Auto Zones, Didn't check anywhere else TBH as I suspected it only happened when using CC accl button and was correct on that part. This problem was unrelated to whats happening now.

That confirms that the problem is NOT the throttle body. The throttle is controlled by the computer.

Matthew, these vehicles are very electrically (computer) connected. I don't understand it all either, but the others here will not guide you into fixing something that doesn't need fixin.
There advice is from many years of knowledge and wisdom.
I know because I fought them only to learn that they were right.

Hi Matthew, :welcomewagon: to the forums!

Here is the how-to thread for the VVT solenoids that you need to replace.
https://www.chevyhhr.net/forums/how-...13-14-a-28779/

Replace those, make sure the gas cap is on tight(couple of clicks), have the codes cleared, and then see how the car does. If you still have issues or the check engine light comes back on, have the codes read and post the numbers here.

Welcome to the site, and don’t go cheap on those VVT solenoids, one member had issues a week or two ago , had to replace the offshore one .
There is a discount code for us at RockAuto, if you choose to do the work yourself.