Got a second-hand door lock mechanism (tested) to replace the one in the driver's door - the car locks/unlocks intermittently. I don't want to get stuck with a mechanism that doesn't work at all with the door stuck closed.

Thing is, the fuel flap doesn't open on occasions when the button/lever is pulled

Does anyone know if the driver's door lock issue is related to the fuel flap? Are they linked in some way? Not much point fixing the door lock if I go to get diesel and can't open the fuel flap?