Hey guys,

2006 2.4 auto 2LT.....I have been trying to chase down this problem for a while and have been researching it for quite some time, my HHR is and auto and after I drive on the highway and exit off the ramp to country roads, or sit at idle for quite some time sometimes my car slams into gear and i have little to no power almost stalling the car, I have replaced, the MAF, MAP, intake and exhaust solenoids, throttle body, TCM (transmission control module) injectors, both oxy sensors, coolant tempature sensor, etc all in the last couple of months, all AC delco parts. Its intermitent and the car rides great when this does not happen. I have 193,000 miles on the car and had it to a transmission (specialist) where they said there was nothing wrong with the trans. I throw a p0172 code when it happens, which means to rich in bank on, hence all the replacement parts i have thrown at it. Where I live everything is ultra expensive bringing it to a so called (professional). I keep thinking its a transmission control soleniod or torque converter but i am not sure. any input would be great. thanks

 

Check the thread by Whopper over 116,000 hits on this site, a cheap and easy fix in refrence to codes P0010 & P0011 I have the 2006 2lt auto, check it out.

 

Jay - he has already replaced the cam actuator solenoids

OP: have you done a search here for the code you are getting?

Your current problem may have nothing to do with any of the previous problems with the transmission - when the car encounters a problem with one of many different sensors, it can go into limp mode, and start to shift rather abruptly. In other words, the hard shifting can be caused by a multitude of things, and many of them not related to a problem with the transmission at all.

 

There are a few thing that will trigger a P0172 code, here are the main culprits.

*MAF failing or failed.
*MAP failing or failed.
*Internal mechanical defect.
*Defective oxygen sensor.
*Defective fuel pressure regulator.
*Defective coolant temperature sensor.
*Defective air temperature sensor.
*Stuck or defective thermostat.
*Ignition misfires.
*Defective throttle position sensor.
*Defective or blocked fuel line.
*Defective or failing fuel injectors.

You've already knocked a few off the list, but with your mileage on the vehicle, I'd strongly suspect a fuel system issue.

Has it ever set a "P" code like P0301-0304?

 

I don't think it has ever set off a "P0301-0304" code, but then again I have an OBII CAN code reader that might not show a code like that, Its weird b/c I never really get a check engine light and when it happens I will plug in my code reader and check it when it happens and it shows that code, I was thinking about a new fuel tank pressore sensor, or a fuel pump b/c it has a built in filter in the pump, but i am not sure, at this mileage it could be anything, its very frustrating. I do not think its mechanical b/c it rides great most of the time without any issues.

 

Does anyone know what p 2468 means? Mine has a similar problem as what you are describing and set the engine light on and set this code?

 

Since your new here, I will try to be easy on you.
You might want to start your own thread on this. I know you said it seems like the same problem as the OP's, but tagging on to the end of another thread usually doesn't get noticed.
Also telling your year model and such would help.
Sooo. Here's a link to the trouble codes on this site:
https://www.chevyhhr.net/forums/problems-service-repairs-42/list-diagnostic-trouble-codes-2008-2010-hhr-14259/

Fwiw.I don't see a P2468, unless I overlooked it.

 

i forgot to mention, when I come to a stop, the car wants to stall or does, but if i put it into nuetral the car is fine, it is weird. thanks again for all the help

 

how about a pluged cat converter

 

I have thought about that also, I am not sure how to diagnose a cat problem, my upper oxy sensor looked messed up when I replaced it, so it could be a culprit as well.