Method and apparatus for detecting errors, fluid pressure, and occlusions in an ambulatory infusion pump

An infusion pump having a motor to drive a plunger slide into a reservoir, wherein the infusion pump is controlled by a processor, the processor performing the steps of:

• receiving a current measurement from the motor;
• storing the received current measurement in a memory;
• comparing the stored current measurement to a threshold current;
• detecting when the plunger slide is seated in the reservoir when the stored current measurement exceeds the threshold current based;
• determining there is a problem with the force sensor if the force sensor independently fails to register a value indicating that the plunger slide is seated in the reservoir;
• and
• wherein the processor further performs:
• measuring movement of the plunger slide by an encoder as encoder counts;
• and signaling an error with the force sensor when the force sensor independently fails to recognize that the plunger slide is seated in the reservoir after a preset encoder count threshold is exceeded.