When I got back in my car (2007 Auto HHR LT 55k miles) today the gauges started bouncing around and my check engine and security light came on. On top of that, it is now shifting in and out of gears very hard.

I took it to Autozone and had the codes read. It turned up P0700, U0073 and U0100.

Thanks for any help.

 

Read through this "Sticky".
https://www.chevyhhr.net/forums/problems-service-repairs-42/list-diagnostic-trouble-codes-2008-2010-hhr-14259/
Sounds like you may have a wiring connection problem and/or a TCM problem.

Maybe someone else with the same symptoms can lead you in the right direction for the fix.

 

Sorry, have news on this? Have exactly the same problems and will go to the dealer for the 4th time. Don't think they'll solve it.

 

If your problem is consistent you are probably lucky, when the problem is intermittent finding the source (wire) of the problem is daunting.

 

Well, taking the car to the service on Wednesday (weekly procedure) and just want to give them some hints. Looks like they are all "modern specialists" - can just read codes and change parts. Something more complex is too hard for them...

 

After another service and 63 EUR bill, no changes. They thought they found the source and changed something related to ignition. Going there again on Thursday. If that won't help, I'll visit one electrician who will probably find the source. Anyway, thinking about selling the car once it's fixed. Dodge Charger was at least 5 times better (except for fuel consumption:)).

 

After 3 repairs - no changes. Now the service are offering me to replace the whole wiring. First of all - it costs quite a lot. I will do it if there are no options, but, maybe, there may be cheaper solutions? I'm not sure that the new wiring will actually fix the car. It's undoubtedly the worst car in my life and I'm not sure it can actually work properly:)