funymuny

Fwiw...posting my experience here in case someone else is scratching their head with a similar issue. My car...2010 GS, purchased new and currently 11,500 miles. Obviously I do not drive it much. This winter the check engine light came on. Used my cheap bluetooth code reader to get the codes. P0172 and 175, basically saying banks one and two are too rich. Hmmm. I may be roundly criticized for what I did next but I know I'm not alone...I simply reset/cleared the codes to see if problem cleared itself. A few weeks later (which may have been 50 miles or so) CEL back on. Same codes. Do some research as to possible causes...can be lots of things when it comes to fuel issues. A new MAF sensor was put in before the warranty ran out but I thought, ok, it's easy to get it out so I'll pull the sensor and clean it well. Done, put it back in and clear the codes. After the next few rides CEL back on, same codes. So clearly something is not right since the problem is not going away.

Take the car to my local non-dealer mechanic. They do the diagnostics and get the same 0172 and 0175 codes. Guess they started looking at the air intake housing and called one of their parts guys. It seems the hydrocarbon pad, which is affixed to the top of the housing with adhesive, had come loose and was blocking the MAF sensor, obviously disrupting air flow and its readings. Apparently the replacement housing is made the same way...no change in the way the pad is attached.

The purpose of the pad is to absorb fuel vapors that MIGHT leak out of the fuel system AFTER the engine is turned off. Apparently there was a time these vapors were considered negligible. My understanding is other manufacturers have different ways of accomplishing this. This Chevy pad is literally about 6" x 6" and aproximately the thickness of typical gasket material. In fact it feels very similar except it has adhesive on one side.

There is a TSB on this issue however the TSB I found did not apply to 2010 or later model years. Anyway, thought I would share. Maybe it will help someone.

Mark

v26278

Thanks for posting, that info could save someone some grief at some point. By the way if the car was running fine I'd do the same thing at first, clear the CEL and see if it came back.

jwf

+1 for me. Haven't had any codes on my vette yet, but on other cars I've seen codes pop up once and then never return.

VET4LES

Thanks for the information.

bucwheat

I had the same thing happen and the dealer says it was the Airaid cold air intake I installed,they cleared the code and it came back about 200 miles later and I cleared it again,have not seen it for over a year now.

dpigguy

Back in early January, 2008, my C6 coupe started throwing the same codes. Working with the engineers in Bowling Green, the codes were stopped and have not return for over 5 years and 46k miles. The solution was to change brand of fuel (was using top tier, went to another) and to tape up the holes in the front bumper support and the seam where the bottom valence meets the engine compartment shroud using metal, a/c tape. It worked! No mention of any interference with a pad in the MAF assembly. I'll have to check it out again.

funymuny

She (mechanic) said it was just loose inside. I am guessing it was partially loose, meaning it was hanging from the top of the air intake. In any event, clearly it disrupts the airflow going to the MAF sensor.

To be fair, my codes could come back. I'll try to remember to report back. But the pad was loose so that issue has been resolved. Occam's Razor comes to mind...the simplest theories are often correct (or something close to that).