I have a 2009 GMC 1500 with 5.3 liter with 2011,000 miles. Almost immediately when starting (and while driving) the smell of fumes enter the cab. They don't smell like exhaust, and I cannot find any leaks in the exhaust system--at least obvious ones. Is the PCV a possibility or something with the EVAP system (ones codes it is throwing)????
Thanks for any direction.