Method and apparatus are disclosed for monitoring and alerting vehicle occupants for ignition systems. An example vehicle includes a cabin, a touchscreen within the cabin, an engine to activate responsive to the touchscreen receiving a passcode, seats within the cabin, occupancy sensor modules to detect occupancy of the seats, and a warning controller. The warning controller is to initiate a timer upon detecting, via the occupancy sensor modules, that an occupant has exited the cabin and emit an alert responsive to the timer reaching a predetermined threshold.