Occlusions in a delivery line of an infusion pump can be detected by measuring pressure differentials in the pump over short periods of time in order to minimize the effects of long term systematic sensor changes. In a delivery mode such as basal insulin delivery where a small portion of a volume of fluid is delivered, pressure readings can be obtained before and after the motor move to deliver each portion and compared. The differentials after one or more motor moves can be compared to determine whether an occlusion is present. In a delivery mode such as bolus insulin delivery in which an entire volume of fluid is delivered, pressure differentials can be obtained for consecutive deliveries at a common point in the delivery cycle of each delivery. Comparison of these pressure values can be used to determine whether an occlusion is present.