Q: Check fuel cap warning flashes, car shuts off

Hello there, in most cases the check fuel cap warning and the vehicle shutting off are not related. The check fuel cap light is shown due to the a leak detected in the EVAP system. When leaks like this occur, they generally do not have any adverse symptoms on the vehicle. If the vehicle is shutting off there may be a larger fuel system issue. The most common would be the fuel pump, fuel filter, charcoal canister, or a fuel line. A qualified technician, such as one from YourMechanic, will be able to inspect your fuel cap warning light and diagnose your stalling issue in order to have the appropriate repairs done.