I got a "check fuel cap" message and my avg.mpg, range, and fuel gauge went screwy.
There was no correlation between mileage, avg mpg and range of miles. I was getting readings of svg mpg of 30+ and range of over 450 miles. The fuel gauge would read half full and I put 7-8 gallons in the tank. The odometer still shows true mileage. I the EVAP and sensors tested at a dealer, no error messages were generated.