I'm having that same issue on my 2006 HHR. Rough idle, P0300, P106 codes. I replaced MAF, MAP sensors and a new battery. Sent it for diagnostic, tested injectors, ground, fuel pressure, and checked for water infiltration. Don't know what else to do. Getting ready to take it to the dealer but can't really afford a huge repair bill.

 

Welcome to the site.

Tagging on to the end of another thread, your post will most likely get overlooked.
Best bet is to start your own thread in the Problems section. Be sure to include as much info/repairs done as possible.

Edit. Wow. Just realized you joined here in 2011 and this was your 1st post.

 

Moved you out into your own thread, as George pointed out, "Tack On" can get overlooked.

A couple of questions, how many miles on your HHR, and have you noticed any coolant loss, or milky deposits on the dipstick or oil fill cap?

 

Thank you! I appreciate that. It has 105k on it and I haven't seen any fluid losses. No milky dipstick or filler cap.

 

Hmmm....Seems like you've worked your way through the commom causes of these codes with no resolution.

Here is a thread that may prove helpful.....

https://www.chevyhhr.net/forums/deleted-threads-41/help-code-p300-random-misfire-19566/

I'm thinking that you might have an issue in the engine wiring harness, but it may take a trip to the dealership to trace it down.

One question I forgot to ask, is it a 2.2 or 2.4?

 

It's a 2.2L. I had heard that a crack in the flex pipe may cause that. Could this be true? It is a stick.

 

Here is a discussion about P0106
http://engine-codes.com/p0106.html

Those 2 codes don't aim at flex pipe. More likely somebody changed the air filter and forgot to reconnect the MAF sensor, or didn't get it tight.

 

No. I checked that too. I replaced the MAF myself along with the MAP sensor. I did read something about the ECM needing to be reprogrammed though

 

If you can get live OBDII readings and watch the intake air temp and manifold pressure and flow, you would get a better handle on it. My $15 adapter from China Bluetoothed to my phone or laptop is capable of that.

Sounds like you are stretching other discussions to fit your symptoms. P0300 is random misfire. P0106 has nothing to do with air/fuel mixture as it relates to O2 sensors.

The 2006 has a single spark pack, so I would think that would be a place to look for random misfires. I am still thinking a wiring problem somewhere under the hood.