Hi,
Been a while since I've been on here.
I have a 2011 hhr lt 2.2 automatic with about 55k. A few months ago I took it in to get diagnosed due to odd driving problems I had experienced. First was that it would randomly sputter when coming to a stop (as if belt was slipping). Second problem was that it would do like a hard shift and had noticed that it would usually happen when using ac. They gave me 3 codes which were the p0740, p0700 and I believe the u800. Did not have time where I could drop it off at the dealership to diagnose since it still had power train warranty. Today, after finally getting my code reader back from family, read codes and received the p0742 code. I still have the aforementioned driving conditions that happen randomly.
I've read a few posts that discuss the codes that I'm receiving but am not to sure what harness to look at to see if it's the culprit. It's there way I can get a pic of where to start looking at, our maybe done advice on what would be causing the driving issues?

 

I found this thread

The HHR has a harness issue at the transmission plug located adjacent to the oil filter. The harness doesn't have enough slack in it to accommodate the flex of the drivetrain and the pins (crappy little crimp on deals that shouldn't have been used) in the connector plug eventually crack and breakoff. The symptoms are pretty consistant...as I described below, the first indicator you are likely to see is the security indicator will come on, and the cruise control will intermittently disengage. Depending on which/how many pins are getting bad connections, the more varied/severe the symptoms. You can confirm this fault by gently pushing in on the plug...you should get a positive connection then and the symptoms will temporarily disappear.

While simply replacing the broken pins will correct the problem, they will continue to fail over time. What I have had done is to extend the harness ~8" to alleviate the strain on the plug during driving. I'll keep everyone informed over the next few months as to how well the fix has worked.

using the search tool

 

I found that one as well, but it was for an 06 and think the oil filter had a new location now.

 

From what I have read about code p0742 most of the time the cause is a stuck tcc valve. Maybe from clutch material stuck in the valve keeping it open or just leaking through.

Your still under warranty which is a good thing because internal trans work may be in your future.

Let us know how you make out.
Here is more info that I have found

http://engine-codes.com/p0742_chevrolet.html

 

Hey clwest,

If you decide that you would like to work with your dealer, and would like some assistance setting it up, let me know! I can be reached via PM. Please include your name, contact information, VIN, current mileage, and your preferred dealership.

Sincerely,

Jonathan A.
Chevrolet Customer Care

 

The oil filter location has not changed. TSB's sometimes don't get the dates changed.

The TCM is under the Darth Vader hood in front of the fuse box. the wires connect to yhe bottom of the trans, you have to get under the car.