2013-2017 Cadillac and other GM vehicles may exhibit hesitation or stalling issues during ambient temperatures of 100 degreesand higher, accompanied by DTCs P2635 and/or P018B. Excessively hot and sustained ambient temperatures can cause vapor buildup in the fuel feed line. Customers can be advised to utilize fuels with octane levels greater than 91, and to refrain from extended idle periods if possible. If the fuel pump is operating correctly, replacing the fuel pump will not correct the vapor condition.