Illumination of the Check Engine Light can be caused by a loose or worn gas cap.
2009 GMC Envoy Problem Reports
Most Reported 2009 GMC Envoy Problem Reports
Electrical power may be lost to the interior of the vehicle due to a blown 125 amp fuse located at the under hood fuse box. This fuse can blow if jumper cables are connected incorrectly. Replacing the blown fuse will commonly correct this problem.