Replaced my MAF Sensor a couple of days ago and all was well. Today the CEL came on so I pulled a code P2098 for the downstream O2 too lean. Maybe not the smartest thing to do but I have been using 89 octane ($4.69 gal) with no problems. I don't remember if it had ethenol in it or not. So my plan is to run the fuel down to 1/4 tank and fill with 93 octane premium fuel ($5.15 gal) and see what happens. Guess it could be other things as well like an exhaust leak or a bad O2 Sensor.

Update: I do have to say that the CEL has always gone on and off the whole 2-1/2 years I've owned the car but didn't own a code scanner till very recently. I also, until last month or two, have been using 91 octane gas.

As I sit here typing I just heard on the local news, Tampa FL, that if people filled up this past weekend we may have contaminated gas. Which i filled up all my vehicles!!!