Infusion devices, systems, and methods can detect a presence or absence of an infusion cartridge in an infusion pump. Embodiments may include a loading sequence, recording loading pulse width modulation (PWM) commands applied to an infusion pump motor during the loading sequence, setting a value of threshold PWM commands based on the commands applied during the loading sequence and comparing values of operational PWM commands applied during pumping operations to the value of the threshold PWM commands. If the value of the operational PWM commands drops below the threshold by a predetermined amount, a missing infusion cartridge warning may be generated.
