I agree that there is a root cause involved here. I have seen it many times on many different gasoline and diesel engines. It is caused by putting electrical components in areas subjected to high temperatures. The components themselves create heat and need air flow to cool them but they are placed in areas with no air flow and subjected to heat from the engines which need to run hot to lower emissions.

We have moved the components that we can away from heat and tried to get air flow on components that can't be moved. On trucks with compressed air systems we have had great success using a 5psi small stream of air on sensors and solenoids. Some equipment we use high speed blowers to cool components.

The basic design of these engines puts the cam actuator solenoids and the coils in the valley on the top of the engine. Heat rises so that becomes a very hot area. Then GM, in their infinite wisdom, made a plastic air cleaner housing that incorporates an engine cover that doesn't allow the heat to escape basically cooking the components. They can try to find wire insulation that won't break down in the heat but it usually requires increasing the size of the component and there isn't always room to do that.

Since he never came back after various suggestions were given, and he gave no response to several questions and suggestions.............. nor responded to what the "fix" was....................... :toast:

There is no "root cause" - from what we have seen they fail due to oil contamination jamming up the screen, the solenoid burns out/dies eventually due to wear (just like door lock solenoids, and other relays), or the wiring is damaged due to improper maintenance. The original "root cause" reference he made, really surprised me when he stated he was a technical service person, yet could not understand the codes/light being cleared by disconnecting the battery for a bit which was mentioned MANY times in the thread (after saying he had read the entire thread).

Anyways, would be interesting to see if cooler air would make a difference at all.

How far back did go to find that one?
No real solution? What is this thread about?

Pretty simple reason for the battery disconnect to only work for a while: that clears ALL of the OBDII monitors, they take time to re run completely.

People need to learn that turning the CEL of does not fix anything. It also will not get you past an emissions test.

This forum rocks. My 2006 2.4 HHR (67K miles) had the check engine light come on about 2 weeks ago. Pulled the codes today and they are the P0013/P0014. As it happens, it started shifting really hard from first to second today. So I will be using the information from this thread to replace both the exhaust and intake solenoids. One thing I have not read in these 52 pages is whether anyone else hears a clunk when shifting from Park to Reverse or Park to Drive with this condition? That was the first noticeable symptom other than the check engine light and was followed by the hard shifting. After arriving home and starting it again later, there was no clunk between Park and Drive and no hard shifting.

Yes a clunk into gear can come from the codes. Of course you could have a mount issue but I would repair the codes first.

The trans shifts hard because when there are some trouble codes the ECM and trans controller adjust some of the operating setting to keep other things from being damaged by a faulty sensor that may be giving some misinformation

Example. When there is a fault code (not all codes) the transmission will ramp up the line pressure to lock in the clutches tighter to guard against slipping when the engine is not preforming correctly. That's why the shifting gets hard and it bangs into gear

Yup the clunking when going from Reverse/Park/Drive is part of the hard, or abrupt, or FIRM shifting - just part of the symptoms for these codes as well as other codes. And yup, it can come and go. Let us know how the repairs go (good move, in my opinion, on changing both solenoids). I'll close your other thread to lessen confusion for the other members now you have found the "fix". Have fun getting your hands dirty. :)

Oh, one other thing - some members have found that the solenoids get "clogged" in the oil passages - likely caused by infrequent oil changes. An oil/filter change alone MAY alleviate the problem and clean out the solenoids - but I'd still go with changing them out, and do a fresh oil and filter change just to show your HHR that you love it. :)

Yesterday I saved a clueless mechanic with this thread.

When I walked in to deliver (4(?) qts of 10W40(?) and a filter) for a 2008 2.2L HHR Panel he was trying to find the exhaust camshaft position sensor. I asked him why, he said he had P0010 and P011 and he read that it was the sensor(?) and that the oil "getting thin" was the problem.

I did direct him to the Intake Solenoid and tried to explain about dirty oil. I don't know why he thought shorting it by a qt was a good idea.

His boss told me "you just got him fired on his first day". To be fair; it's a big truck shop.

But you saved the HHR's engine a slow rattleing death!

Another win for Whopper's tutorial and my HHR. I did not threaten the best time but got both the intake and exhaust solenoids replaced, changed the air filter and followed up with an oil and filter change. All seems well. I got the gray clips out with no problem but still struggled to get the connectors off the top.