What typically is thought of as a fuel cap code is actually a code to indicate a leak in the evap system.... The gas cap is part of that but so is many feet of vacuum hose, the fuel tank, a vapor storage tank... It won't effect drivability but if you have emissions testing it won't pass with a light on....
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
