The OBDII reports the alcohol % to a TechII scanner and many other scan tools, not all. My ScanmasterELM software and my $12 bluetooth adapter does.

If you are not buying E85 on purpose, I might be suspecting the sensor in the gas tank, I think it's part of the fuel pump.

When I put "P0172" into the search box 8 pages of results spit out.

The computer reports the alcohol content to the OBDII reader. There is a sensor in the gas tank, part of the fuel pump IIRC. If you are not putting E85 in the tank, maybe the sensor has gone wonky.

The OBDII code is supposed to tell the technician where to turn his book to start further testing. All too many of them got their training at Advance AutoZone PEP as a tool to sell parts. We have been hearing a lot of people lately getting caught in the "throw parts at it until goes away" tornado, it surprises me that it's Official GM shops doing it.

Hey, I think I missed something......

If your car is E85 certified how is the 65% alcohol to high and affecting the performance? E85 is 85% alcohol.....no???

I think that the basic issue is a dealer or dealer's tech who isn't versed in the proper diagnostic procedures, coupled with the typical service department "upsell" mentality.

Now if there is really that much alcohol in the fuel, and as the OP stated, he doesn't use E-85....then the gas station may have a tank filled with the wrong juice.

That can happen, not too long ago a local gas station got their tank filled with diesel accidentally, around 100 cars had to be fixed on their dime.

[QUOTE=843de;726103]Check your PM, and sorry for the late reply.

To me it sounds like a dealer that's bypassing the proper diagnostic procedures and going for your wallet with the classic "upsell" of a "Fuel System Service".

To me, the first step is always suspecting a dirty, failed, or loose MAF sensor.

http://www.obd-codes.com/p0172[/QUOTE

Please pardon my ignorance but where is the MAF sensor located?

(Check out post #18 below....843de)

No I have never used E85 gas. I have always used regular gas that's 87 octane rated or higher. Well if it is the sensor in the gas tank that should be a covered repair under the manufacturers warranty hopefully.

I found the results for the code in the search engine thanks. I had a typo in my search which threw everything off. Yes I too am very surprised at the poor troubleshooting abilities of these GM mechanics but I think its just this particular GM shop. There are a few others in my area so I will be giving them a visit.

The MAF sensor is part #14 in this diagram, it's easy to get at once you've removed the airbox. It should only be cleaned using "MAF Sensor Cleaner" available at your local auto parts store.

One important thing to remember, DO NOT under any circumstances touch the sensor elements, just let the cleaner blast away any deposits. If you touch the sensor elements, it's pretty much ruined.

http://parts.nalleygmc.com/images/pa...231T03-003.JPG

ooooo I like that picture. Downloaded for future reference.

Easy to understand, gets the job done, and suitable for framing. What more could you ask for?;)