Can you shed a little light on its location and connection. My mechanic's references don't mention it, but mine is the first HHR he's played with.

 

You've gotten excellent replies so far, but since I started this thread, I'll offer this. Many, but not all, states allow some gas to be sold ethanol free. In particular, small engines and motorcycles with long non-running times have problems with the ethanol. StaBil products help a lot. Boats have real problems in their high moisture environments; ethanol absorbs water and the fuel does strange things.

I try very hard, despite the 30 to 35 cent/gallon difference here in South Carolina, to use ethanol free in my motorcycle and mower type equipment. I will use E10 in the bike when I'm "sure" I'll use all or most of the tank in a week or so, but it will have ethanol free AND StaBil if it's going to sit for several weeks.

I'm not at all sold on ethanol as having ANY advantages except to the corn growers; helping them is a political decision. I PERSONALLY THINK it degrades engines and fuel systems. I PERSONALLY KNOW it degrades fuel economy. Opinion is that it is more expensive per mile in fuel cost, but that is arguable.

You've seen the pure-gas.org link; there is also an android app, and I think an iOS app.

 

Get a new mechanic if he cannot locate the fuel pump assembly. It is a one piece unit in the fuel tank, it will cost about $300. Depending on your particular car a new wiring pigtail may be required because GM changes harnesses so much.

 

I copied the info below off of a GM PDF file that I stumbled across. It was in reference to a 2008 or 2009 HHR.

The flex-fuel 2.2L doesn’t require a special fuel sensor. The first flex-fuel engines used a light-reactive sensor to measure fuel composition from 100 percent gasoline to 85 percent ethanol. The 2.2L has a virtual sensor—software programmed in the E37 ECM with no separate physical sensor whatsoever. Based on readings from the oxygen (O2) sensors, fuel level sensor and vehicle speed sensors, the ECM adjusts the length of time the fuel injectors open for the type of fuel used. Within a few miles after filling up, the E37 controller determines what fuel is powering the 2.2L I-4 and manages the engine accordingly.

 

Well, I stand corrected! Come to think of it, I wondered why the fuel pump is cheaper for the 2011 model than the pre 2009 model.

So it could be an O2 sensor problem. Never hurts to try new O2 sensors over 70,000 miles.

 

not the fuel pump assy, the module connection which gives specific gravity

 

So I'm kinda back to half of the original question ... this information suggests that the O2 MIGHT be what is causing erroneous results ... 31% with ethanol free ... ... what are the results of an erroneous result, just the long term trim data? Or does it cause the rich condition reported?

 

I think we're circling around a drain here, metaphorically speaking, so let's address the elephant or O2 sensor in the room.

By its definition, P0172 - system too rich bank 1, is fairly straightforward. Unless you're dealing with an inline engine with Upstream and Downstream O2 sensors like we find in every HHR.

As pointed out in the thread you linked in your first post, an imbalance between the 02 sensors is a possibility, either due to a failing flex pipe or one of the two sensors pooping out.

Another common trigger for our friend P0172, is a dirty or failing MAF sensor, that will either cause the engine to run rich or lean...thereby throwing off the Oxygen levels in the exhaust. That will send the output of the O2 sensors out of range, triggering the code.

And lastly, there is a possibility of a fuel delivery issue. Be it low fuel pressure, or an injector that's getting "hung" and leaking excess fuel, which will cause the affected cylinder to run rich...but not necessarily rich enough to misfire and trigger a P0301-P0304 misfire code.

The high ethanol readings are spurious in nature, as least to my thinking, and I'd concentrate on the O2 and MAF sensors first, including a careful check of the flexpipe. I just had the flex joint on my '06 fail in the last two weeks, besides being utterly obnoxious to listen to, it set a P0172 which I cleared after having the flex joint repaired.

Instead of adding to the complexity of the problem, eliminate the simple stuff first.

As a final caveat, there is just the slightest chance that the start of your problems and having the recall done are not coincidental. But that would be making a broad, and hard to prove, assumption that the technician didn't disconnect the Negative battery cable before he or she started working on your vehicle...and possibly damaging a module in the process.

 

Not to mention that sometime "lean" does not mean lean. It just means that the sensors think it's lean, like a vacuum leak an exhaust leak a stuck EVAP solenoid. Or, "rich" does not mean rich for similar reasons.

 

I'm of the opinion the O2 sensor is what I'll try if it occurs again after switching back to my TopTier E10 fuel. BTW, I recorded data over an hour or so with a refueling about half way through ... that ethanol calculation is weird ... as are the short and long term trims.

A graph of the info ... https://drive.google.com/file/d/0B2G...ODg/edit?pli=1

Thanks everybody!